nio
igh S hool
Physical Science
Quarter 1 - Module 1
Formation of Elements
Polarity of Molecules
.
Table of Contents
What This Module is About ............................................................................................... i
What I Need to Know ........................................................................................................ ii
How to Learn from this Module......................................................................................... ii
Icons of this Module ......................................................................................................... iii
What I Know ................................................................................................................... iii
Lesson 1:
Formation of Heavier Elements ................................................. 1
What I Need to Know ................................................................................ 1
What’s New: Galaxy’s Puzzle ............................................................................. 1
What Is It ................................................................................................... 2
What’s More: Comprehensive Reading ..................................................... 4
What’s More: (Formation of Elements: An Analogy) .................................. 5
What I Have Learned: Origin of Elements ................................................. 6
What I Can Do: In the News ...................................................................... 7
Lesson 2:
Synthesis of New Elements in the Laboratory ......................... 8
What’s In ................................................................................................................ 8
What I Need to Know ................................................................................ 8
What’s New: Hidden Words ........................................................................ 9
What Is It .................................................................................................. 10
What’s More: Evolution of an Atom’s Representation ....................................12
What I Have Learned: Synthetic Elements ............................................... 12
What I Can Do: Bomb Leftovers ...............................................................13
Lesson 3:
Polarities of Molecules ............................................................... 14
What I Need to Know ................................................................................ 14
What’s New: Opposites ............................................................................. 14
What Is It ................................................................................................... 15
What’s More: Creative Approach to Polarity .............................................. 16
What’s More: Molecules out of Clay .......................................................... 17
What I Have Learned: Polarities Lesson.................................................... 18
What I Can Do: Polarities at Home ............................................................ 18
Lesson 4:
Properties of Molecules According to their Polarity ............... 19
What I Need to Know ................................................................................ 19
What’s New: Hidden Words ....................................................................... 19
What Is It ................................................................................................... 21
What’s More: Polarity at Work ................................................................... 22
What’s More: Molecular Sketches ............................................................. 23
What I Have Learned: Explore Your Chemicals ......................................... 23
Summary
Assessment: (Post-Test)
Key to Answers .................................................................................................................. 26
References ........................................................................................................................ 28
What This Module is About
For the Students
This module will introduce you to the world in a deeper level. What you have learned
from your elementary years to your junior high years about science have prepared you to enter
and understand the new lessons you are about to get to know: from the theoretical start of the
universe to the behavior of molecules as observed through the microscope.
You might be intimidated by the depth of the lessons but don’t be disheartened. This
module is constructed to teach novices and inspire. If you ever find yourself lost or confused
amidst your learning, don’t hesitate to approach your teacher. Remember, unhealed confusion
will hinder effective learning.
Welcome to Module 1 of your Senior High School Physical Science. Happy learning!
For the Facilitators
This module aims to educate the students in the simplest way possible. Teachers and
parents must accommodate the learner to aid them in learning. Facilitators must avoid giving
direct answers but rather give help to the learners on how to acquire answers. Do not hesitate
to notify the teacher for concerns and ask further assistance.
The following are the lessons contained in this module:
Lesson 1 Formation of Heavier Elements
Lesson 2 Synthesis of Elements in Laboratories
Lesson 3 Polarities of Molecules
Lesson 4 Properties of Molecules Based on Their Polarities.
What I Need to Know
At the end of this module, you should be able to:
1. Give evidence for and explain the formation of heavier elements during star
formation. (S11/12PS-IIIa-1);
2. Explain how the concept of the atomic number led to the synthesis of new elements
in the laboratory. (S11/12PS-IIIb-11);
3. Determine if a molecule is polar or non polar given its structure. (S11/12PS-IIIc-15);
4. Relate the polarity of a molecule to its properties. (S11/12PS-IIIc-16)
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How to Learn from this Module
To achieve the objectives cited, you are to do the following:
• Take your time reading the lessons carefully.
• Follow the directions and/or instructions in the activities and exercises diligently.
• Answer all the given tests and exercises.
Icons of this Module
What I Need to
Know
This part contains learning objectives that
are set for you to learn as you go along the
module.
What I know
This is an assessment as to your level of
knowledge to the subject matter at hand,
meant specifically to gauge prior related
knowledge
What’s In
This part connects previous lesson with that
of the current one.
What’s New
An introduction of the new lesson through
various activities, before it will be presented
to you
What is It
These are discussions of the activities as a
way to deepen your discovery and understanding of the concept.
What’s More
These are follow-up activities that are intended for you to practice further in order to
master the competencies.
What I Have
Learned
Activities designed to process what you
have learned from the lesson
What I can do
These are tasks that are designed to showcase your skills and knowledge gained, and
applied into real-life concerns and situations.
I
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What I Know
Multiple Choice. Select the letter of the best answer from among the given choices.
1. Which theory suggests that the universe began from a singularity and its inflation?
A. Big Bang Theory
B. Eternal Inflation
C. Oscillating Universe
D. Steady-State Universe
2. Aside from the neutron, the core of an atom is made up of which other subatomic
particle?
A. electron
B. positron
C. proton
D. None of the above.
3. What kinds of elements has atomic numbers greater than Uranium?
A. alkaline earth metals
B. metals
C. noble gases
D. transuranium elements
4. What’s the term for stars that are nine times bigger than our Sun?
A. massive stars
B. nebulae
C. stars
D. supernova
5. What does an element’s atomic number determine?
A. number of electron
B. number of positron
C. number of proton
D. None of the choices
6. What does an element’s atomic weight determine?
A. number of protons and electrons
B. number of protons and neutrons
C. number of protons only
D. number of neutrons only
7. Who developed the latest model of the atom which is accepted until today?
A. Ernest Rutherford
B. J.J. Thomson
C. John Dalton
D. Niels Bohr
8. How long can super heavy elements live?
A. hours
C. seconds
B. minutes
D. microseconds
9. What does adding neutrons to atoms make?
A. a new compound
B. a new element
C. a new isotope
D. None of the choices
10. What serves as the identity of an atom?
A. number of electron
C. number of proton
B. number of positron
D. None of the choices
11. What causes the formation of heavier elements in space?
A. death of a star
B. neutron-star merger
C. supernova
D. All of the choices
12. What is the last lighter element to be formed during a star formation?
A. Helium
B. Hydrogen
C. Iron
D. Oxygen
13. Who solved Dmitri Mendeleev’s arrangement of the periodic table?
A. Albert Einstein
B. Ernest Rutherford
C. Henry Moseley
D. John Dalton
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14. What force naturally pulls things together?
A. fission
C. gravity
15.
B. fusion
D. pressure
Which element is the first and lightest to ever be formed?
A. Helium B. Hydrogen
C. Iron
D. Oxygen
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Formation of Heavier Elements
What I Need to Know
At the end of this lesson, I should be able to:
1. Give evidence for and describe the formation of heavier elements during star
formation and evolution;
2. Understand the basic concept of star formation;
3. Know that the chemical elements from Hydrogen to Iron can be formed in the stars
through stellar fusion;
4. Counteract misconceptions about the formation of heavy elements;
5. Understand the importance and necessity to keep updated the progress of scientific
concepts.
What’s New
ACTIVITY 1.1.1 The Galaxy’s Puzzle
Instructions: A. Read the short story provided below and find the 5 words related to physics
and chemistry. Use items 1-5 as a guide to find the words.
Once, there was a spy named Hydrogen (nicknamed Hy) with massive issues on
trusting Angela, his agency partner. There was always the possibility that their opinions crash
against each other rather than end in a peaceful fusion like when Hy suggests the suspect of
the crime they were investigating could be in the East Coast but Angela argues that the place
should be in the West Coast. They were almost fired from the job for being too unprofessional,
almost becoming the ‘big bang’ to their careers. The gravity of the situation made Hy and
Angela rethink their attitude and agree to be more understandable of each other’s differences
on opinions.
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B.Chemistry and Physics words found in the story:
1. This is the lightest element in the periodic table.
2. This is what happens when elements combine together,
usually resulting to new elements.
3. This is the theory which proposes the universe is still in the
process of inflation.
4. This is the term for stars bigger than our own Sun.
5. This is what pulls atoms together and what causes the Earth
to orbit the Sun.
VOCABULARY
 Big Bang Theory: this is the currently accepted theory of the origin of the universe
which proposes that everything started from a singularity which in time inflated—and
continues to do so—until the world we know of today started existing approximately 14
billion years ago.
 Stellar Nucleosynthesis: this is the birth of elements through nuclear fusion that
takes place within stars.
 Supernova: this is the explosion in the event of a death of a star.
 Neutron-Star Mergers: this is when stars merge to form a more massive star,
generating more energy than normal stars.
 Light Elements: these are elements from Hydrogen to Iron which form in less massive
stars.
 Heavy Elements: these are elements heavier than Iron which form from massive
stars, supernovae, or neutron-star mergers.
What Is It
Among the proposed explanations on how the universe began, the Big Bang Theory
is the one currently accepted, theoretically. It describes that the universe started with a
singularity defined simply as a point where all matter, time, space, laws of the universe and
reality itself are condensed—ultimately inflating (not exploding) since approximately 14 billion
years ago until now, according to NASA (National Aeronautics and Space Administration).
Before the planet we live in right now came to existence as all the other planets and
solar systems and galaxies, the earliest elements were formed first.
Let us explore why the elements needed to exist first: all matter that makes up most of
the universe—including us—are made up of elements. These elements are what we study
about in the Periodic Table such as Hydrogen (H), Oxygen (O), and Gold (Au). Now we need
to understand the foundations and formations of elements.
This lesson primarily focuses on the formation of the heavier elements but in order to
understand that, we must first understand how the lighter elements were formed.
3
The steps below summarize the formation of the earliest and lighter elements in the
heart of massive stars, stars that are nine (9) times the size of our Sun:
1. There is first a huge cloud of Hydrogen (H) atoms. As per the law of the universe,
gravity will pull these atoms together.
2. The core (center) of this cloud will get dense and hot, like when more things rub together
they get hotter and more compressed. This dense and hot core will start to ignite.
3. This ignition is the start of fusion and since the atoms that are fusing (clumping together)
are Hydrogen atoms, this is called Hydrogen Fusion happening in the core of the cloud.
*KEEP IN MIND: When the Hydrogen fusion takes place, this doesn’t mean that
ALL the Hydrogen atoms are already fusing. The rest of the Hydrogen atoms
that are farther from the core remains outside the core. This trend happens not
only with Hydrogen but also with other elements when they start to fuse at a
later stage of element formation.
4. The heated core eventually becomes plasma: a soup of electrons and nucleuses that
are not as well-formed, explaining why they aren’t atoms yet.
5. Hydrogen atoms will eventually fuse into Helium (He) and this (He) is now the new core.
The surroundings of this (He) core is the previous (H) now called H-shell or H fusion
shell.
Figure 1.1 Shows the fusion of the isotopes of Hydrogen atoms to form a Helium atom.
6. Since the remaining H-shell are also constantly fusing into the (He) core, more (He) is
formed building up. With this (He) build-up, where gravity pulls atoms inward, there is
also pressure which pushes the H-shell outward causing the size of the star to get
bigger.
7. Steps 1-6 are going to continue until other fusions starts to happen:
a. He fuses with H into a Carbon (C) core with a He-shell outside it;
b. C fuses with He into Oxygen (O) core with a C-shell outside of it; and so on until Iron
(Fe).
8. Why do we stop at Fe? It’s because in order to produce another element after Fe, more
energy is needed than what the existing fusion can supply. That does not mean only
the elements from H to Fe are real elements. Heavier elements continue to form where
there is enough energy: during supernovae (plural of supernova—when stars explode
and die) and neutron-star mergers (when stars merges).
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Now that we have cleared the basics of how the lighter elements are formed, we go
in-depth on how the heavier elements get formed—one concept still unknown to science but
supported by theories.
Stellar Nucleosynthesis is one of the ways heavier elements are formed.
Nucleosynthesis explains how new atomic nucleus are formed from nucleons preceding
from the new ones. There is also Nuclear Fusion, a process where neutrons and protons
combine to new atoms. Nuclear fusion is how elements Hydrogen, Helium and small amounts
of Lithium and Beryllium were formed.
*REMEMBER: The number of protons (+) is the identity of an element, not the number
of neutron (+) nor the number of electrons (-).
What’s More
ACTIVITY 1.1.2A Comprehensive Reading
Instructions: Read the given passages and answer the questions that follow. This activity aims
to practice your analysis on scientific articles, specifically about the basic formation
of elements.
“Heaviest Elements Did Not Form from Supernovae”
Source: Physics Today (Frebel and Beers 2018)
Unitil now it is accepted that heaviest elements formed from a supernova.However,
scientists Anna Frebel from the Massachussets Institute of Technology (MIT) in
Cambridge and Timothy C. Beers from the University of Notre Dame in Indiana have found
evidence contrary to that belief.
A supernova explosion happens when a star dies. This explosion, like any other
explosion, would generate enough heat but in this case, such heat would aid the formation
of elements. Since the lighter elements up until Iron can take form from normal stars, there
are still questions about how the elements after Iron have taken form to which most studies
proposed to be from supernovae.
From the study of Anna Frebel and Timothy Beers, heaviest elements tend to form
in an environment filled with free neutrons. This is vital because these free neutrons would
be captured eventually into an existing nucleus making it heavier. The new element will
not be this heavier nucleus but the one formed after this nucleus decays. Such decay
would become stable and thus becomes this new, heavier element with a very short
lifespan of a millisecond.
The big revelation was that such an event with enough energy can only happen
during a neutron-star merging. Neutron-star merger is when two stars collide due to
gravitational pull and results in a much bigger explosion than a standard supernova.
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Questions:
1. What is the major finding of Anna Frebel and Timothy Beers’ 2018 study?
2. Why do you think their finding is important to the field of scientific education?
3. What could have happened if the new evidence about the formation of the heaviest
elements had not been discovered?
ACTIVITY 1.1.2B Formation of Elements: An Analogy
Instructions: Read the the procedure carefully. Make sure before doing this activity that your
materials are complete.
Objective: Understand how the formation of elements works through an analogy.
Materials:
 Colored clays (3 separate colors, at least 1-inch ball each)
 Permanent marker
 any smooth paper to serve as a surface
 1 whole sheet of paper
Procedure:
1. Assign each color as 1A, 2B, and 3C. This will be the information you will put on your
paper as reference. 1A, 2B, and 3C will serve as element examples. Make sure to take
a picture with the procedures as evidence.
2. Now, make little balls out of one of the colored clays. Make the balls equal in size. This
wil be your 1A element atoms. Make as many as your clay would allow while setting
aside the other 2 colored clays.
3. Now, merge 2 of the 1A atoms and keep merging two balls of the 1A atoms.
4. When merged, cover the merged 1A atoms with a new colored clay. This now becomes
an analogy of the birth of a new element, 2B.
5. Continue covering the merged 1A atoms with the 2B atom color.
6. Notice that while the new atom 2B has been formed, the atom also becomes heavier.
7. This time, merge two 2B atoms together until all of them are merged by two.
8. The merged 2B atoms should now be covered with your last colored clay for it to
become the atom 3C. Set your merged clays aside and follow through step 9.
9. On your paper, answer the following questions:
a. In all honesty, did this activity aided your learning about the formation of elements?
Please justify your answer.
b. What did the colored clays represent?
c. What did the merging of the clay balls represent?
10. End of activity
PARTS
POINTS
Materials
Questions
TOTAL POINTS:
6
10 (with pictures)
10 (with 1 picture per
procedure, total of 8)
20/20
What I Have Learned
Activity 1.1.4: Origin of Elements
Instructions: In your household, choose one member of your family to be your partner.
The purpose of this activity is to strengthen your acquired knowledge through sharing
the topic verbally. This method helps improve memory retention and confidence in the lesson.
What you will do is to tell your partner about what you have learned today about the
formation of the stars and elements. After this, make sure to ask your partner the following
questions and write her/his answer on a sheet of 1 whole paper.
1. What was the process of the formation of lighter elements?
2. Is this lesson new to you?
3. Are you satisfied knowing the origins of the elements? Please justify your answer.
Make sure that you take a picture of you and your partner’s mini discussion about the
formation of elements at home. This picture must be sent to your teacher as part of the overall
score. Happy learning!
What I Can Do
Activity 1.1.5: In the News
Instructions: To broaden your understanding that this lesson can be applied in real life,
research and read about the elements that can be found in our blood and bones.
Use the following table below and copy the format on a 1 whole piece of paper.
Date of the Article’s Publication:
Score:
/10
Title of the Article:
Reference/s:
1. What did you learn from the article?
2. Which elements can be found in a human’s blood and bones?
3. What was the connection of the article you read to the lesson about the formation of
elements?
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Lesson
2
Synthesis of New Elements in
the Laboratory
What’s In
We have discussed that the lighter elements from Hydrogen to Iron were formed
through stellar nucleosynthesis in the cosmos or simply, space after the events of the Big
Bang.
However, there are elements that need so much energy that it needs to be recreated
in the laboratory in a controlled environment in order to be recorded here on our planet. This
does not mean that these heaviest elements are not possible in space—they are but their life
span can only last for a such a little time before ceasing to exist which makes obtaining
evidence of them hard.
What I Need to Know
At the end of this lesson, I should be able to:
1. Explain how the concept of atomic number led to the synthesis of new elements in
the laboratory;
2. Understand the synthesis of an element in a laboratory;
3. Know the importance of the periodic table of elements
What’s New
ACTIVITY 1.2.1. Hidden Words
Instructions: Find the hidden words inside the box of letters and encircle them. Use the
words you found to match them with the guide sentences that follow.
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A
G
B
Y
H
N
E
D
T
E
A
F
T
D
E
V
O
H
E
N
R
Y
F
R
O
S
D
E
J
B
P
Q
A
S
I
I
M
C
G
G
L
B
L
A
N
G
U
N
I
J
F
D
A
A
O
S
S
K
K
G
C
U
A
O
S
I
Y
D
U
U
T
T
W
G
O
S
D
T
Y
U
R
T
O
D
E
L
E
M
E
N
T
B
A
O
S
E
I
Y
T
A
W
L
I
B
N
M
A
F
G
K
Y
G
C
J
R
G
I
P
E
C
H
K
G
A
S
K
A
T
U
N
D
L
T
S
D
O
Q
R
L
R
M
I
G
O
Y
D
N
P
A
E
O
E
H
A
T
K
N
V
B
L
A
F
P
S
R
D
R
J
F
D
O
T
V
U
Y
H
T
W
G
H
Guide Sentences:
DOWN
1. This is the term for the combined number of protons and neutrons.
ANS:
2. This is what the heaviest elements are called.
ANS:
3. This means that one part of a molecule is either more positively-charged or
negatively-charged, to be discussed in Lesson 3.
ANS:
ACROSS
4. He was the one to fix Mendeleev’s periodic table of elements.
ANS:
5. This is formed during the Big Bang, with Hydrogen as an example.
ANS:
VOCABULARY
 Synthetic Elements: refers to the chemical elements formed in a laboratory through
certain, man-controlled processes.
 Transuranium Elements: these are elements heavier than Uranium.
 Isotopes: these are the same atoms with different number of neutrons.
 Atomic Number: this is the number of protons in an atom, pertaining to its identity.
 Atomic Weight: this is the number of protons and neutrons together of an atom.
 Periodic Trends: the chemical properties exhibited by the elements, reflected in the
periodic table through groups or families.
9
What Is It
The heaviest elements in the universe can be recreated in a laboratory. This type of
element creation is called the synthesis of elements which is the focus for this lesson.
It is important to note that these heavy elements, although created in a laboratory, do
exist in space. The main reason why these heavy elements are needed to be created here in
our planet is because traces of them in space cannot be harvested. The reason for this is
becuase their life spans are too short to be captured for evidence—microseconds short to be
exact.
Let us take the following scenario for example: the element Gold (Au) is too heavy that
whenever it takes form in spcae, it dissipates almost as soon as it was formed.
Back on 1913, a scientist named Henry Moseley sought to fix Dmitri Mendeleev’s
arrangement of the periodic table of elements. There was a discovery that arranging the
elements based on their weight didn’t reflect the element’s chemical properties properly. Henry
Moseley experimented by shooting electrons at varying elements. The result was that the
elements released x-rays at a certain frequency that increases as the protons increases.
Based on Henry Moseley’s x-ray spectroscopy experiment, he opted to arrange the
elements in the periodic table according to the square root of their unique frequency emission
resulting in a more organized table which shows periodic trends more clearly. Moseley’s xray spectroscopy is vital in the synthesis of the heaviest elements in a laboratory because it
serves as a foundation of discovering that manipulating an element’s number of protons can
be done.
SYNTHESIS OF ELEMENTS
An element is identified by its number of protons because no two elements can have
the same number of protons. So in order to make a new, heavier element, protons must be
added to an existing atomic nuclei of an element.
A cyclotron—a type of particle accelerator—is a device invented and used to form
and accelerate protons to hit a target nuclei, causing an addition of a proton to the target
element.
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Figure 2.1 Shows the simple mechanism and model of a cyclotron.
Figure 2.2 Shows the simple mechanism and model of a particle accelerator.
What are the elements synthesized here on Earth? These elements are those termed
as transuranic elements and those written at the bottom of the periodic table of elements
which are the heaviest in terms of atomic number, considered when heavier than Uranium (U)
with an atomic number of 92.
TRANSURANIC ELEMENTS
There are 26 transuranic elements in total, as follows:
Atomic
Number:
Element
Symbol:
Element
Name:
Atomic
Number:
Element
Symbol:
Element
Name:
93
94
95
96
97
98
99
100
101
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fermium
Mendelevium
102
103
104
105
106
107
108
109
110
No
Lr
Rf
Db
Sg
Bh
Hs
Mt
Ds
Nobelium
Lawrencium
Rutherfordium
Dubnium
Seaborgium
Bohrium
Hassium
Meitnerium
Darmstadtium
11
Atomic
Number:
111
112
113
114
115
116
117
118
Element
Symbol:
Rg
Cn
Nh
Fl
Mc
Lv
Ts
Og
Element
Name:
Roentgenium
Copernicium
Nihonium
Flerovium
Moscovium
Livermorium
Tennessine
Oganesson
What’s More
ACTIVITY 1.2.2 Evolution of an Atom’s Representation
Instructions: Answer accordingly. Ask your teacher for clarifications.
Objectives: 1. Analyze how the model of an atom changed over time;
2. How the different models help us better understand th concept of the atomic
number.
Procedure:
1. Research about the following models of the atom in order:
a. John Dalton’s model
b. J.J Thomson’s model
c. Ernest Rutherford’s model
d. Neils Bohr’s model
e. Erwin Schrodinger’s model
2. On a piece of 1 whole paper, draw the simple versions of their models (in order) and
add notes on the bottom about the highlights of their model.
3. Answer the question: What made the scientists change the atomic models so much?
What I Have Learned
Activity 1.2.3 Synthetic Elements
Instructions: In your household, pick one member of your family to to be your partner.
10 points
The purpose of this activity is to strengthen your acquired knowledge through sharing
the topic verbally. This method helps improve memory retention and confidence in the lesson.
12
What you will do is to tell your partner about what you have learned today about the
concept of atomic number led to the synthesis of new elements in the laboratory. After
this, make sure to ask your partner the following questions and write her/his answer on a sheet
of 1 whole paper.
1. How did Henry Moseley arrange the periodic table of elements?
2. Is this lesson new to you?
3. Are you satisfied knowing that man can recreate an element using technology? Justify
your answer.
Make sure that you take a picture of you and your partner’s mini discussion about the
formation of elements at home. This picture must be sent to your teacher as part of the overall
score. Happy learning!
What I Can Do
Activity 1.2.4: Bomb Leftovers
Remember that during star explosions, heavier elements are created? That same
concept happens here on Earth when a nuclear bomb explodes. When a nuke explodes,
traces of radioactive elements such as Uranium and those heavier than it are left in the wake
of the explosion. These radioactivity can be hazardous to the health of the people near the
area.
Instructions: To broaden your understanding that this lesson can be applied in real life,
research and read about the Chernobyl Nuclear Incident focusing on the
topics of radiation and its effects. Use the following table below and copy the
format on a 1 whole piece of paper.
Date of the Article’s Publication:
Score:
/10
Title of the Article:
Reference/s:
1. What did you learn from the article?
2. What heavy element was the Chernobyl nuclear accelerators supposed to make?
3. What was the connection of the article you read to the concept of atomic number led
to the synthesis of new elements in the laboratory?
13
Polarities of Molecules
What’s In
We have discussed about the synthesis of elements using technology whenever such
elements cannot exist unless created. In this lesson, we will look further into the trends of
atoms and a group of atoms, also called as molecules—more specifically into their polarities.
What I Need to Know
At the end of this lesson, I should be able to:
1. Determine if a molecule is polar or non-polar given its structure;
2. Give the scientific definition of polarity;
3. Identify a molecule’s polarity;
What’s New
ACTIVITY 1.3.1 Opposites
Instructions: To ready you for the next lesson, this activity will give you an idea on the general
concept of polarity. Use a one whole piece of paper to make a simple sketch of
the given situations below, following the criteria:
Area
Creativity
Neatness
Definition
This is the creative use of the story format
as a medium to communicate knowledge
of a topic.
This is the readability of your written
output and its neatness.
14
Percentage
%
Points
60
6
40
4
100 %
10 per
item
Situations:
1. Tony and Steve playing on a seesaw, with Steve the heavier one on the left.
2. An infinity sign with the left side bigger than the right.
3. A Yin-Yang
VOCABULARY
 Polarity: refers to the overall charge of a molecule
 Molecule: a group of elements bonded together
 Positive charge: refers to an atom or a molecule with an excess proton
 Negative charge: refers to an atom or a molecule with an excess, unpaired electron
 Electronegativity (EN): the tendency of an atom/element to attract an electron,
resulting in a negative charge, hence the name.
What Is It
Before anything else, it is important to note that a molecule is held together by bonds.
These bonds are like the ropes which holds together a makeshift roof outside your house
except in a subatomic level, these bonds are either polar or nonpolar.
A polar bond is generally an unfair bond: one is more tight while the other is rather
loose. In chemistry, this bond refers to an ionic bond—a result of an unequal and big
difference in electronegativities of elements involved in the bond. On the other hand, a
nonpolar bond is a fair bond: the electronegativities of the elements concerned are equal, as
well as the sharing of electrons (this usually occurs in covalent bonds). In analogy to the
rope, visualize this bond as something with both ends of the rope equally tied tight.
DETERMINING THE POLARITY OF A MOLECULE
The easier and more basic way in determining the polarity of a given structure is
through the Lewis structure and some solving, given the following steps and examples:
1. First, recall how to draw the Lewis structure and apply it to an example. In this case, let’s
have the molecule CO2 (more commonly known as carbon dioxide.
*IF UNFAMILIAR, kindly ask your teacher to review about how to draw Lewis
structures.
Lewis structure of C𝑂2:
O
C
O
2. Find the electronegativity (EN) difference of each bond. Use a periodic table of elements
for this.
If the EN difference of the bond is greater than 0.4, it is polar but if it is lesser than 0.4,
it is nonpolar. If ALL of the bonds in the molecule is nonpolar, the molecule is
automatically nonpolar. However, if one bond is polar, continue with the steps.
In the case of C𝑂2, the EN difference is 0.89 which is greater than 0.4. In this stage
we can assume that C𝑂2 is polar.
15
3. If the central atom has no lone pairs (unpaired electrons) with all of the other atoms
around it the same, the molecule is considered to be nonpolar. If the central atom has
lone pairs (unpaired electrons) with all of the other atoms around it different, the molecule
is possibly polar.
In the case of C𝑂2, the central atom C has no lone pairs around it and the atoms around
it are identical. In this stage, C𝑂2 is now nonpolar.
4. Your teacher will teach you how to draw a sketch for the molecule which will essentially
help you identify if the molecule is asymmetrical (polar) or symmetrical (nonpolar).
In the case of C𝑂2, the sketch will show that this molecule is symmetrical (evenly
distributed). The final judgement for the C𝑂2 molecule is that it’s nonpolar.
What’s More
ACTIVITY 1.3.2A Creative Approach to Polarity
Instructions: On a ½ crosswise sheet of paper, make a creative story about the lesson of
polarity of molecules. You can use your own characters and analogy but make
sure they are in-line with the main concepts of the lesson. It could be sci-fi, humor,
drama, or in a script format—you decide. Your short story will be graded
according to the following criteria:
Area
Significance
Creativity
Grammar
Punctuation
Neatness
Definition
This is the connection of the story to the
scientific concept discussed (polarity of
molecules)
This is the creative use of the story
format as a medium to communicate
knowledge of a topic.
& This is the proper use of the English
(American) language in terms of
grammar and punctuation.
This is the readability of your written
output and its neatness.
16
Percentage
%
Points
30
6
30
6
20
4
20
100 %
4
20
ACTIVITY 1.3.2B Molecules out of Clay
Instructions: Make sure to follow the procedure and secure the materials are ready.
Materials:
 Clay (of 2 colors)
 2 sticks of about 3 inches in length
 Permanent marker
Procedure:
1. First, wait for your teacher to show you and the rest of the class the VSEPR model of
the water molecule (H2O).
Note for the Teacher: provide images of the VSEPR models required.
2. Next, use one colored clay for Hydrogen and the other to Oxygen. For Hydrogen,
make a bigger ball and mark it with a permanent marker with H. For Oxygen, make 2
smaller balls and mark them with O each.
3. Use the sticks to connect the clays as referenced by the image provided by the
teacher. It should look like an inverted V.
4. Using your new individual models, let the teacher discuss the polarity of water and
listen carefully.
5. Wait for your turn to show the class your model and to discuss what you know of it in
terms of the lesson.
6. End of the activity.
PARTS
Materials
Questions
TOTAL POINTS:
POINTS
10 (with pictures)
10 (with 1 picture per procedure,
total of 5)
20/20
What I Have Learned
ACTIVITY 1.3.3. Polaritiy Lessons
Instructions: In your household, choose one member of your family to be your partner.
The purpose of this activity is to strengthen your acquired knowledge through sharing
the topic verbally. This method helps improve memory retention and confidence in the lesson.
What you will do is to tell your partner about what you have learned today about the
polarities of molecules. After this, make sure to ask your partner the following questions and
write her/his answer on a sheet of 1 whole paper.
1. Do you think the polarity of a molecule matters on a larger scale?
2. Where do you think can this lesson be applied to in daily life?
17
Make sure that you take a picture of you and your partner’s mini discussion. This picture
must be sent to your teacher as part of the overall score. Happy learning!
What I Can Do
ACTIVITY 1.3.4 Polarities At Home
After this lesson, try to look at the common objects you can see in your house and
even those outside school with new eyes: how polarity plays a role on their overall figure and
look. From the water to the air around you: their polarity at work!
Instructions: To broaden your understanding that this lesson can be applied in real life,
research and read about the polarity of the following chemicals: isopropyl
alcohol, ammonia, vegetable oil, candle wax, acetone, and hydrogen
peroxide. Use the following table below and copy the format on a 1 whole
piece of paper.
Title of the Article/s:
Date of the Article’s Publication:
Reference/s:
Score:
/7
1. Which chemicals from the list are polar?
2. Which chemicals from the list are non-polar?
18
Lesson
Properties of Molecules
According to their Polarity
4
What’s In
In the previous lesson, we have discussed about the polarity of molecules and how to
determine if a molecule is polar or nonpolar.
What I Need to Know
At the end of this lesson, I should be able to:
1. Relate the polarity of a molecule to its properties;
2. Identify the properties of a molecule.
What’s New
ACTIVITY 1.4.1 Hidden Words
Instructions: Find the hidden words inside the box of letters and encircle them. Use the
words you found to match them with the guide sentences that follow.
H
B
A
S
E
D
F
K
L
Y
H
F
S
O
L
P
F
R
Q
B
V
S
E
D
A
N
B
H
J
K
S
W
M
I
L
Y
P
R
O
P
E
R
T
I
E
S
C
E
J
A
I
D
F
A
J
O
L
T
Y
U
O
G
L
E
W
L
B
S
T
F
S
D
R
T
I
N
S
O
J
V
I
A
R
G
D
E
N
D
D
P
O
E
N
G
P
E
G
R
G
C
I
W
R
N
G
O
O
W
U
K
P
V
I
N
N
A
P
N
S
R
B
H
O
E
L
B
U
L
O
S
F
B
B
U
I
S
H
I
E
S
I
L
R
S
E
N
N
E
G
K
N
K
N
N
E
J
N
F
T
W
D
L
E
A
T
E
H
S
F
E
D
A
A
M
S
W
D
F
T
D
19
Guide Sentences:
DOWN
1. This is the temperature at which liquid starts to boil.
ANS:
2. This is the temperature at which liquid starts to melt.
ANS:
3. This is the term for molecules which have a slightly negative or positive side.
ANS:
ACROSS
4. These are what determines the behaviour of a polar/non-polar molecules.
ANS:
5. This is what a material would be called if they easily mix with water or any solvent.
ANS:
VOCABULARY
 Properties: this refers to the behaviour of an entity or an object.
 Solubility: this is a physical property that refers to the ability of a molecule to dissolve
in a solvent.
 Melting point: this is a property that refers to the temperature when a molecule starts
to melt.
 Boiling point: this is a property that refers to the temperature when a molecule starts to
boil.
What Is It
Molecules do not have the same properties, which contributes to the wonderful
diversity of things around us and the different ways such things react with the world. One of
the major factor that determines what properties molecules have is their polarity.
The first property we will discuss is the solubility. This is the ability of a molecule to
be dissolved in a solvent. Another property is the melting point—temperature when a
molecule starts to melt or transition into a liquid state. The next property is the boiling point—
temperature when a molecule starts to boil or transition into a gaseous state.
The following examples will cover examples of the correlation of polarity and the
mentioned properties:
20
SOLUBILITY
 The general law for solubility among molecules is that polar molecules can be dissolved
in polar solvents (polar to polar) and nonpolar molecules can be dissolved in nonpolar
solvents (nonpolar to nonpolar). An example to this is salt (NaCl) which is polar. Have
you noticed that it can easily be dissolved in water (H2O)? This is because water is polar,
too.
 As opposed to salt, oil (containing Carbon and Hydrogen only) is nonpolar. Have you
seen what happens when oil and water are mixed? They separate. This is because water
is polar. Oil, being nonpolar, can only be dissolved in a nonpolar solvent.
MELTING AND BOILING POINT
 Polar molecules usually have Hydrogen bonds. Hydrogen bond is a big thing in bonding
because this means a stronger attraction. Therefore, polar molecules have a stronger
attraction as opposed to nonpolar molecules. What does this mean for both the melting
point and boiling point? The stronger the attraction, the higher both the melting and
boiling point given that they are of the same sizes.
What’s More
ACTIVITY 1.4.2 Polarity at Work
Instructions: Make sure to follow the procedure carefully and that your materials are ready.
Objective: Understand how properties of molecules behave due to polarity works in a larger
scale.
Materials:
 Tablespoon of oil
 Tablespoon of salt
 Tablespoon of sugar
 4 glasses of clear water, separate
(considred as 2 points as one)
 1 bottle of nail polish
 clean spoon for stirring
 permanent marker
 1 whole sheet of paper
Procedure:
1. In each glass , label them accordingly with A, B, C, and D.
2. On your paper, write the following table:
Molecules:
A.
B.
C.
D.
When Mixed in Water:
Oil
Salt
Sugar
Drops of nail polish
21
3. On the second column, “When Mixed in Water” answer them one by one and mix
your samples in their designated glasses of water.
4. Answer the following questions below the table on your paper:
a. Which sample of molecules did not dissolve in the water?
b. Which sample of molecules dissolved in the water?
c. If water is polar, what is the polarity of the molecules that didn’t dissolve in the
water?
d. If water is polar, what is the polarity of the molecules that dissolved in the water?
5. End of activity.
PARTS
Materials
Table Answers
Questions
TOTAL POINTS:
POINTS
16 (with pictures)
8 (2 points each item)
10 (with 1 picture per procedure,
total of 4)
34/34
What I Have Learned
ACTIVITY 1.4.3 Explore Your Chemicals
Directions: In your household, pick one member of your family to be your partner.
The purpose of this activity is to strengthen your acquired knowledge through sharing
the topic verbally. This method helps improve memory retention and confidence in the lesson.
What you will do is to tell your partner about what you have learned today about the
properties of the molecules based on their polarities. After this, make sure to ask your
partner the following questions and write her/his answer on a sheet of 1 whole paper.
1. What are 2 common household chemicals that you consider polar?
2. What are 2 common household chemicals that you consider polar?
3. In your own words, what is solubility?
Make sure that you take a picture of you and your partner’s mini discussion. This
picture must be sent to your teacher as part of the overall score. Happy learning!
What I Can Do
ACTIVITY 1.4.2 Molecular Sketches
Instructions: Answer accordingly.
22
Objective: Find out a molecule’s polarity thorugh a series of scienctific steps.
Materials:
 Periodic table of elements (can be printed from a source in the internet, with the source cited) or
can be store-bought.
 1 whole sheet of paper
Procedure:
1. Research on the following molecules:
a. CO2
b. OF2
c. CCl2
d. CH2Cl2
2. For each of the molecules listed above, find their:
a. Molecular geometry
b. Individual bond EN difference
c. Verdict if polar or nonpolar
3. Submit your answer sheet to your teacher
Summary
Overall, we have learned that the earliest elements were Hydrogen and Helium,
formed during the birth of a star. The heavier elements after Iron were formed during the death
or merging of a stars. The evidence for this can be found in everyday objects, including our
bodies that are made up of elements. The birth of stars can be traced back to the theory of
the Big Bang as the origin of the universe.
Synthesis of new elements are made possible here on Earth through the technology
of particle accelerators. The basis for this synthesis goes all the way back to the concept of
atoms and the arrangement of the periodic table.
We also learned that it is possible to identify the polarity of a molecule using its
structure or the steps provided. Knowing the polarity of a molecule is important because it
affects the overall behavior of a molecule and sheds light on why a certain molecule has
certain properties unique to it which will be discussed in depth on the next lesson.
Polarities affect the properties and behaviors of molecules, as shown by their solubility,
melting and boiling points. The concept of this lesson is important because it explains normal,
daily things at a micro perspective.
23
Assessment: (Post-Test)
Multiple Choice. Answer the question that follows. Choose the best answer from among
the givenchoices.
1. Which invention helped synthesize elements on
Earth?
A. bombs
B. magnets
C. particle accelerators
D. All of these
2. What refers to the ability of a molecule to be dissolved in a solvent?
A. boiling points
B. melting points
C. solubility
D. surface tension
3. What refers to the certain temperature for a molecule to transition into a gaseous state?
A. boiling points
B. melting points
C. solubility
D. surface tension
4. What is the explosion during a death of a star commonly called?
A. neutron-star merger
B. supernova
C. synthesis
D. fusion
5. Which of the following can determine a molecule’s polarity?
A. EN difference
B. Lewis structure
C. molecular geometry
D. All of these
6. What theory on the origin of the universe is currently accepted today?
A. Big Bang theory
B. Eternal Inflation
C. Oscillating Universe
D. Steady-State Universe
7. What is the term for elements heavier than Uranium?
A. light elements
B. heavy elements
C. transuranic elements
D. None of these
8. What is the term for elements which were born first during star formation?
A. light elements
B. heavy elements
C. transuranic elements
D. None of these
9. Which of the following DOES NOT determine a molecule to be nonpolar?
A. central atoms has no lone pairs
B. EN difference is less than 0.4
C. symmetrical in structure
D. None of these
10. Who fixed Dmitri Mendeleev’s arrangement of the periodic table of elements?
A. Albert Einstein
B. Henry Moseley
C. J.J. Thomson
D. John Dalton
11. What force pulls matter together?
A. gravity
B. pressure
C. polar bonds
D. None of these
12. What is formed when the core of a star becomes heated?
A. heavy elements
B. light elements
C. plasma
D. transuranic elements
13. At which element does element formation stop in massive stars?
A. Helium
B. Hydrogen
C. Iron
D. Lithium
14. How many transuranic elements are there?
A. 20
B. 23
C. 26
D. 94
15. This is the ability of an atom to attract electrons.
A. electronegativity
C. polarity
B. fusion
D. synthesis
24
25
Senior High School
Physical
Science
Quarter 1-Module 2
Week 3: Intermolecular Forces
Week 4 : Biological Macromolecules
26
TABLE OF CONTENTS
Page
What This Module Is All About
What I Need To Know
How To Learn From This Module
Icons For This Module
i
i
i
ii
Lesson 1: Intermolecular Forces
What I Know
What’s In
What’s New
What is it
What’s More
What I Have Learned
What I Can Do
Assessment
1
3
4
5
9
10
11
12
Lesson 2: Biological Macromolecules
What I Know
What’s In
What’s New
What is it
What’s More
What I Have Learned
Assessment
15
17
17
18
26
27
28
27
What this module is all about
This module covers the following MELCS (1) Describe the general types of
intermolecular forces, (2) Explain the effect of intermolecular on the properties of
substances, and (3) explain how the structures of biological macromolecules such as
carbohydrates, lipids, nucleic acid, and proteins determine their properties and function.
Lesson 1 in this module will help the learner to understand that there is a force of
interaction other than intramolecular forces that exists between molecules called as
intermolecular forces. Students will also learn how these forces affect the properties and
structure of some substances and why this substance exist as liquid and others not.
Lesson 2 emphasizes the importance of biological macromolecules in our body
which includes carbohydrates, proteins, lipids, and nucleic acid. The structures of these
macromolecules will also be given emphasis since it affects their properties and function.
What I Need to Know
After going through this module you are expected to:
1. Describe the general types of intermolecular forces (S11/12PS-IIIc-d-17)
2. Explain the effect of intermolecular forces on the properties of substances
(S11/12PS-IIId-e-19)
3. Explain how the structures of biological macromolecules such as
carbohydrates, lipids, nucleic acid, and proteins determine their
propertiesand function. (S11/12PS-IIIe-22)
How to learn from this Module
To achieve the objectives of this module, do the following:
•
•
•
•
Read the lesson carefully. Take your time.
Follow instructions in doing the activities. Do it diligently.
Be honest in doing the activities.
Check your understanding by answering the post test at the end of
themodule.
i
Icons for this module
ii
Lesson
1
Intermolecular Forces
What I Know
Direction: Read each statement carefully. Write the letter of your answer in your notebook.
1. The following are intermolecular forces of attraction EXCEPT
A. Covalent bond
C. Hydrogen bond
B. Dipole-dipole
D. London Dispersion
2. It is the weakest intermolecular attraction which is formed due to
temporarydipole.
A. Dipole-dipole
B. Ion-dipole
C. Hydrogen bond D. London Dispersion
3. Which of the following will most likely form a hydrogen bond?
A. HCl
B. HI
C. HF
D. H2S
4. What type of intermolecular forces of attraction that holds Cl2 --- Cl2 molecules
together?
A. Dipole-dipole B. Ion-dipole
C. Hydrogen Bond D. London Dispersion
5. Which of the following statement DOES NOT describe Hydrogen
bonding? Hydrogen bond is…
A. a bond between hydrogen and the highly electronegative atoms N, O, F
B. a bond formed between a partial positive hydrogen in a polar molecule and
a slightly negative atom in another molecule
C. a very strong dipole-dipole interaction
D. the weakest form of intermolecular force
6. The following atoms participate in hydrogen bonding EXCEPT
A. C
B. F
C. O
D. N
7. Dissolving sodium chloride in water results to what type of intermolecular
interaction?
A. Dipole-dipole
C. Ion-dipole
B. Hydrogen bond
D. London Dispersion
1
8. What type of intermolecular force of attraction is present as indicated by the
arrow below?
H
A. Dipole-dipole
B. Hydrogen bond
Cl
H
Cl
C. Ion-dipole
D. London dispersion
9. The type of intermolecular force which is a result of unequal sharing of
electronsresulting in a partially positive and partially negative end is called_
A. Dipole-dipole
C. Ionic bond
B. Hydrogen bond
D. London Dispersion
10. Which intermolecular forces of attraction exist in H2S ----- H2S?
A. Dipole-dipole, London forces
C. Ionic, London dispersion
B. Hydrogen bond, London dispersion
D. London – London
11. The type of intermolecular forces of attraction that exist in all molecules is
A. Covalent bond
C. Hydrogen bond
B. Hydrogen bond
D. London Dispersion forces
12. Substance with
intermolecular forces will have _________ boiling
point.
A. Stronger, lower
B. Stronger, higher
C. Weaker, higher
D. Weaker, the same
13. Which of the molecules has the highest boiling point?
A. HBr
B. HCl
C. HF
D. HI
14. Which of following compounds should have the lowest boiling point?
A. HF
B. H2O
C. NH3
D. O2
15. Which of the following compounds most likely have the highest boiling point?
A. C2H6
B. C3H8
C. C4H10
D. C5H12
2
What’s In
Have you ever wonder how sugar totally mixed up with water. What happenedto the
particles of sugar? Where did it go? Is it gone? But you noticed that the water taste sweet
which means that sugar is still there.
Do you still remember your lessons in Grade 9 where you learned that atoms
chemically combined to form compound? The chemical attractions that held the atoms
together in a compound are referred as intramolecular forces. These forces of attractions exist
between atoms. In water for example, the atoms of hydrogen chemically combined with the
atoms of oxygen to form water molecule.
There are three types of intramolecular forces namely: (1) Ionic bond formed when
there is transfer of electrons and is usually formed between a metal and non- metal; (2)
Covalent bond is a bond formed when there is sharing of electron. This type of bond exists
between two non-metal atoms. There are two types of covalent bonds. A polar covalent bond
(formed when there is unequal sharing of electrons between two combining atoms, and nonpolar covalent bond (formed by equal sharing of electrons); and (3) metallic bond is formed
between positively charged atoms in which the free moving electrons are shared forming a
crystal lattice.
The forces of attraction that holds together sugar and water molecule in a mixture is
another type of attraction called intermolecular force. These forces of attraction exist
between molecules which hold them together.
Going through this module will help you understand the different intermolecular forces
of attraction that exists between molecules. You will also learn from this module that the type
of intermolecular forces present in the substance is responsible for its properties.
3
What’s New
Activity 1. FIND ME
Find and encircle the words in the puzzle.
D
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Boiling Point
Intramolecular
Non-polar
Covalent bond
Ion-dipole
Polar
Dipole-Dipole
Ionic bond
Surface Tension
Hydrogen Bond
London Dispersion
Vapor Pressure
Intermolecular
Melting point
Viscosity
4
What is It
Intermolecular forces are forces that exist between molecules, atoms, or ions.
Intermolecular forces of attraction are weaker than intramolecular in terms of energy involved
however; intermolecular forces are responsible for the properties of molecules. The
intermolecular forces explain why substance exists as solid, liquid or gas at room temperature.
The following are the types of intermolecular forces.
Ion-dipole Interaction
An ion-dipole interaction is the force of interaction that exists between charged
particles called ions and a polar molecule. When NaCl dissolves in water, NaCl dissociates to
form Na+ ion and Cl- ion. Since water is a polar molecule, it has apartial positive end and partial
negative end. Thus, the Na+ ion from the NaCl molecule will attract the partially negative end
of the water molecule, while the Cl- ionof NaCl will also attract to the partially positive end of
the water molecule (Figure 1).
Ion-dipole
:
Fig. 1. Ion-dipole Interaction
Dipole-Dipole Interaction
Dipole- dipole interaction is the force of attraction that exists in polar molecule like
HCI. The unequal sharing of electrons between Hydrogen and Chlorineatoms in HCl creating
a partially positive pole in H and partially negative pole in Cl and is referred as DIPOLE (Figure
2).
Hδ+
Clδ-
Hδ+
Dipole-dipole
Fig. 2. Dipole-dipole interaction
5
Clδ-
In dipole-dipole interaction, the molecules with permanent dipoles attract eachother in
way that the positive end of one molecule attracts the negative end of the other molecule.
Hydrogen Bond
The bond that exists between water molecules is Hydrogen bond (Fig.3). It is a special
kind of dipole-dipole interaction between Hydrogen which is a polar molecule and a highly
electronegative elements Fluorine, Oxygen and Nitrogen. In Hydrogen bond, the highly
electronegative element F, O, N causes the hydrogen to become strongly positive.
Hδ+
Hδ+
Oδ-
Oδ-
Hδ+
Hδ+
H-bond
Fig.3. Hydrogen bond in water
The ability of water to form H-bond relates to its ability as a universal solvent. Hbond prevents the water from evaporating quickly into the atmosphere. It also causes ice to
float in water since at freezing temperature, water molecules tend to form a crystal lattice as
it expands.
London Dispersion Forces- is present in all molecules. It is the weakest intermolecular force
which is formed due to temporary dipoles of a non-polar molecule. The strength of the
dispersion forces increases as the molecular weight of the substance increases.
Activity 2
Unscramble the letter to tell what property is being described in thestatement.
1.
2.
3.
4.
5.
_ (Bilniog pniot) is the temperature at which the vapour
pressure of a liquid is equal to the external pressure (Chang, 2015).
(Vcisitoy) measures how well the substance flow.
(Sfrucae tnsioen) measures the toughness of the surface
of the liquid.
(Mltineg pniot) is the temperature at which a substance
changes from liquid to gas.
(Vopar perussre) is the small amount of gas that can be
found above all liquid?
6
Activity 3. Let me FLOAT!!!
Materials:
 Glass
 Water
 Powdered pepper (paminta)
 Liquid detergent
 dropper
Procedure:
1. Fill the glass with about three-fourth full of water.
2. Sprinkle a pinch of powdered pepper (paminta) on the surface of the water.
Observe.
Did the pepper floats in water?
_
3. Put a drop of liquid detergent on the surface of the water. Observe.
What happen to the pepper as you put a drop of liquid detergent to the water? _
_
Chemical bond holds atom together in a molecule, this type of interaction is called
Intramolecular It is the interaction that exist within the molecule. Intermolecular forces on the
other hand, are the force of interaction that exists between molecules. Though this type of
interaction is weaker than intramolecular force it greatly affects the properties of substance.
In the activity, when you sprinkle powdered pepper (paminta) on the top of the water,
it floats on the surface. When a drop of liquid detergent touches the surface of the water, it
breaks the surface tension of the water thereby allowing the pepper to sink in the water.
Surface Tension – is a property of the surface of the water caused by the cohesive
forces (intermolecular forces) between molecules which allows liquid to create a thin film on
its surface.
The stronger the intermolecular forces, the stronger the surface tension. The H-bond
in water produces a high surface tension in water; thus, allowing the paper clip floats in water.
Substance with weaker intermolecular forces will have lower surface tension.
Boiling Point – is the temperature at which the vapour pressure of a liquid isequal
to the external pressure (Chang, 2015).
Melting Point – is the temperature at which a substance begins to change
from solid to liquid.
In general, substance with stronger intermolecular force (IMF) will have higherboiling
point than substance with a weaker intermolecular forces. The strong intermolecular force of
the substance holds the molecules tightly thus making the bond hard to evaporate and boil.
Viscosity – is the property of substance resistance to flow. In general, stronger
IMF means high viscosity.
7
Vapor pressure – is a measure of the tendency of a material to change into the
gaseous or vapor state, and it increases with temperature. A liquid with weak intermolecular
forces will evaporate easily thus, has a higher vapor pressure while liquid with strong IMF will
not easily evaporate thus will have lower vapor pressure.
What’s More
Enrichment Activity: Do this…
1. Identify the possible intermolecular force attraction in the following:
a. NaCl ------ H2O
b. NH3------- NH3
c. H2S -------- H2S
d. O2-------- O2
e. HCl ------- HCl
f. CH3OH ------- CH3OH
g. H2 ------------ H2
h. Na2S ------- HCl
i. Br2 -------- Br2
j. H2O ----- H2O
2. Arrange the following compounds (H2O, H2S, Br2, NaCl) in increasing….
a. Boiling Points
_
b. Melting Points
_
c. Surface Tension
_
d. Vapor Pressure
_
e. Viscosity
_
8
What I Have Learned
Let’s summarize it!









Intramolecular forces are forces that holds atom together in a molecule.
Intramolecular forces are forces between molecules. Ion-dipole, dipoledipole, Hydrogen bond and London Forces or Van der Waals Forces.
Ion-dipole is the force of interaction that exists between charged particles
called ions and a polar molecule.
Dipole-dipole interaction is the force of attraction that exists in polar
molecule. In dipole-dipole interaction, the molecules with permanent dipoles
attract each other in way that the positive end of one molecule attracts the
negative end of the other molecule.
Hydrogen bond- is a special type of dipole-dipole interaction where
Hydrogen bond to highly electronegative elements Fluorine, Oxygen and
Nitrogen. In Hydrogen bond, the highly electronegative element F, O, N
causes the hydrogen to become strongly positive.
London Dispersion Forces- is the weakest intermolecular force which is
formed due to temporary dipoles of a non-polar molecule.
Intermolecular forces affect the properties of substance such as boiling
point, melting point, surface tension, vapor pressure, and viscosity. In
general, the stronger the intermolecular forces the higher the boiling point,
melting point, surface tension and viscosity of the substance. However, in
terms of vapor pressure, the stronger the intermolecular the substance has
the lower its vapor pressure.
It also follows that, the larger the molecule, the stronger the intermolecular
force it has.
The relative strength of intermolecular forces is shown in figure 4 below:
London
Dispersion
Forces
Dipoledipole
interaction
Hydrogen
bond
Ion –
dipole
interaction
INTERMOLECULAR FORCES
Weakest
Ionic bond
INTRAMOLECULAR
Strongest
Fig. 4. Relative strength of intermolecular forces
9
What I Can Do
In this activity will let you understand the effect of attractive forces to viscosityof a
substance.
Materials Needed:
-
a tablespoon of sample liquids (water, oil, condensed milk,
chocolate syrup)
timer
Procedure:
1. Get one tablespoon of each liquid.
2. Get ready with the timer.
3. Pour liquid one at a time and record the time it takes the liquid to hit
theground. Record your observation.
4. Repeat if needed.
Guide Questions:
1. Which liquid flow freely to the ground?
_
2. What would be the reason why some liquid some liquid flow freely while
others did not?
_
10
Assessment
Direction: Read each statement carefully. Write the letter of your answer in yournotebook.
1. What type of bond exists between oxygen (O2) molecules?
C. Covalent bond
D. Dipole-dipole
C. Hydrogen bond
D. London Dispersion
2. It is the weakest intermolecular attraction which is formed due to temporary dipole.
A. Dipole-dipole
B. ion-dipole
C. Hydrogen bond D. London Dispersion
3. Which of the following substances will exhibit dipole-dipole intermolecular forces?
A. N2
B. CH3OH
C. CO2
D. H2S
4. The following atoms participate in hydrogen bonding EXCEPT
A. C
B. F
C. O
D. N
5. Dissolving sodium chloride in water results to what type of intermolecular
interaction?
A. Dipole-dipole
C. Ion-dipole
B. Hydrogen bond
D. London Dispersion
6-10. Refer to the following option
A. Dipole-dipole
B. Hydrogen bond
C. Ion-dipole
D. London dispersion
What type of intermolecular forces of attraction that exists between the following
molecules?
6. NH3------- NH3
7. Li2S -------- H2O
8. N2 -------- N2
9. HBr -------- HBr
10. H2 ------- H2
11. Which of the following intermolecular forces has the highest boiling point?
A. Dipole- Dipole
C, Ion-dipole
B. Hydrogen Bond
D. London Dispersion
12. The type of intermolecular forces of attraction that exist in all molecules is
A. Covalent bond
C. Hydrogen bond
B. Hydrogen bond
D. London Dispersion forces
11
13. Substance with
pressure.
A. stronger, lower
B. stronger, higher
intermolecular forces will have
vapor
C. weaker, lower
D. weaker, the same
14. At which temperature would you expect water to have the greatest vapour
pressure?
A. 100o
B. 75o
C. 9o
D. 0o
15. Which of the following compounds most likely have the lowest boiling point?
A. C2H6
B. C3H8
C. C4H10
D. C5H12
12
Answer Key
13
Lesson
4
Biological Macromolecules
What I Know
Direction: Read each statement carefully. Write the letter of your answer in your notebook.
1. The following compounds are biological macromolecules EXCEPT
A. Carbohydrates
C. Lipids
B. Carbon Dioxide
D. Proteins
2. Which of the following biomolecules is important in muscle building?
A. Carbohydrates
C. Nucleic Acid
B. Lipids
D. Proteins
3. Carbohydrates contains the following elements EXCEPT
A. Carbon
C. Nitrogen
B. Hydrogen
D. Oxygen
4. Which of the following monosaccharide is most abundant in nature?
A. Glucose
C. Maltose
B. Lactose
D. Sucrose
5. A disaccharide which is mainly found in milk and other milk products is
A. Glucose
C. Maltose
B. Lactose
D. Sucrose
6. Which of the following is the building block of proteins?
A. Amino Acid
C. Nucleic acid
B. Enzymes
D. Phosphate
7. What macromolecule is represented in the figure below?
Image Retrieved: June 19, 2020 at
https://rb.gy/f7d1ig
A. Carbohydrates
B. Lipids
C. Nucleic Acid
D. Proteins
14
8. Proteins found in connective tissues like tendons and ligament is
A. Collagen
C. Keratin
B. Fibroin
D. Myoglobin
9. A type of protein which carries oxygen from the lungs to the bloodstream is
A. Collagen
C. Hemoglobin
B. Keratin
D. Myoglobin
10.A A type of lipid which contain a hydrophilic end and a hydrophobic end is
A. Fatty acids
C. Phospholipids
B. Oils
D. Wax
11. The following are the nitrogenous bases found in DNA EXCEPT
A. Adenine
C. Guanine
B. Cytosine
D. Uracil
12. Proteins are polypeptide that contains repeating units of
A. Amino acids
C. Glucose
B. Fatty acids
D. Phosphate
13. Amino acids in proteins are joined together by
A. Glycosidic bond
C. metallic bond
B. Hydrogen bond
D. Peptide bond
14. Enzymes are substances that catalyze a reaction. Which of the following is NOT
an enzyme?
A. Glycopase
C. Pepsin
B. Lipase
D. Sucrase
15. Deoxyribonucleic acid (DNA) carries genetic information of the cell. A DNA
molecule contains the following EXCEPT
A. Fatty acids
C. Pentose sugar
B. Nitrogen bases
D. Phosphate group
15
What’s In
Every living organism is made up of cells, the very tiny units of life. Within the cells are
organic molecules which joined to form larger molecule.
There are four classes of macromolecules as you have learned in your Grade 10
Chemistry. These include carbohydrates, proteins, lipids and nucleic acid forming a chainlike
structure called polymers. Recall that these macromolecules composed mainly the elements
like carbon, hydrogen, oxygen and other macromolecules have nitrogen and phosphate in
their structure.
In this module, the structure of these macromolecules will be given emphasis. The
students will then explain how the structure affects the properties and functions of
macromolecules.
What’s New
Activity 1. Carbohydrates
Study the structure and answer the question below.
Fig. 1. Structure of simple monosaccharides.
Image: Retrieved June 15, 2020 from https://rb.gy/cigwad
1. What are the elements you notice in the structures? _
__
2. What do you notice with the carbon: hydrogen: oxygen (C: H: O) ratio in each
structure? (Note: To answer these count the number of C, H, and O in the
structure.
16
3. Now, look at the structure below.
a. Did you see any similarities with the three structures? _
_
b. Do they have same kind of elements?
c. What differences did you noticed with their structures? _
A.
B.
C.
Figure 2. Different Structures of Carbohydrates
Images retrieved: June 16, 2020 from (a) https://commons.wikimedia.org/wiki/File:Beta-DGlucopyranose.svg (b) https://rb.gy/qglpvk, (C) https://rb.gy/enzuad
1. Carbohydrates
In the activity above, you noticed that all the structures contain the same elements C,
H, and O. These structures are carbohydrates. Carbohydrates are one of the macromolecules
which contain carbon, hydrogen and oxygen only with a ratio 1:2:1.This can be written as
CnH2nOn, where n corresponds to the number of carbon atoms. The term carbohydrate comes
from the Latin word saccharum which means sugar.
The carbohydrate that we eat which is our main source of energy is converted into
glucose which is readily used in the body. It is classified as simple sugars (monosaccharides
and disaccharides) and complex sugars (polysaccharides).
17
Monosaccharides are sugar with one saccharide units. Glucose (used as dextrose
and sugar found in blood), galactose (found in milk and other milk products), and fructose
(sugar found in fruits and honey) are monosaccharides. Theyare isomers which mean, they
have the same molecular formula but different structural formula. The difference in their
structures (Figure 2) is the one that made also difference in their properties like boiling point
galactose has higher boiling point than glucose. Glucose is sweeter than galactose.
Disaccharides are sugar with two saccharide unit joined by a glycosidicbond. Maltose
is a disaccharide formed from 2 Glucose units and is found in malt. Sucrose found in regular
table sugar contains glucose and fructose units. Lactose found in milk and milk products is a
disaccharide containing Glucose and Galactose units.
Polysaccharides are sugar contains many saccharide units. Starch and Cellulose are
polysaccharides. Starch, a storage form of glucose in plants and cellulose, the structural
material in plant cell wall composed of 250 - 400 glucose molecules connected via α-1-4glycosidic bond.
Fig. 3. Starch
. Retrieved June 19, 2020 from http://sphweb.bumc.bu.edu/otlt/MPHModules/PH/PH709_BasicCellBiology/PH709_BasicCellBIology_print.html
18
Activity 2. Pair Me
Pair column A with the description in column B. Write the letter of your answerin the
space provided.
Column A
Column B
1. Collagen
A. carries oxygen from the lungs to the
Bloodstream
2. Keratin
B. Substance used to speed up a reaction
3. Hemoglobin
C. major insoluble fibrous protein found in
connective tissues
4. Enzymes
D. fibrous protein in hair, skin, and nails
5. Fibroin
E. strongest natural fibers found in silk
2. Protein
Protein was believed to be the beginning of life. It comes from the Greek word proteios
which means first. Carbon, Hydrogen, Oxygen, and Nitrogen are the elements that make up
a protein. Sulfur and other metals can also be found in some proteins. Proteins as one of the
macromolecules that are made from multiple units of simple molecules called amino acids
(shown in figure below). Combination of 20 amino acid joined by a peptide bond makes a
protein. Thus, proteins are called polypeptides. The structure of amino acid is shown in the
figure 4.
Fig 4. Structure of Amino Acid
Retrieved June 19, 2020 from https://www.researchgate.net/figure/General-structure-of-aminoacids_fig1_322686460
Each type of protein is made up of different combination of amino acid arranged in
specific way. The order to which the amino acids are arranged
19
determines the configuration and function of protein. Examples of proteins asmentioned in
the activity are the following:
Collagen - found in connective tissues such as tendons, ligaments, skin, cartilageand the
cornea of the eye.
Fibroin/Silk protein – one of the strongest natural fibers found in silk
Keratin - a fibrous protein in hair, skin, and nails.
Myoglobin - contains a heme group contains an iron (II) ion at its center whereoxygen is
being stored.
Hemoglobin - is a globular protein that carries oxygen from the lungs to thebloodstream
Enzymes on the other hand, are substances that catalyze a reaction. The followingare
examples of enzymes and their specific function.
1. Lipase - help in digestion of fats
2. Pepsin - help in breaking down proteins into peptides (smaller units)
3. Sucrase - help in the digestion of sugars and starches
Activity 3.
Study the structure below and answer the following question.
Fig 5. Structure of Triglyceride
Image Retrieved June 19, 2020 from
https://courses.ecampus.oregonstate.edu/ans312/one/lipids_story.htm
1. What have you notice with the structure of triglyceride?
2. What elements compose the structure?
20
_
3. The structure below is a phospholipid.
Fig. 6. Structure of Phospholipid
Retrieved June 19, 2020 from https://rb.gy/yzlhjw
a. What did you notice with the structure of phospholipid compared to
glyceride?
b. Does it have the same components with glycerides? _
_
c. Have you notice any difference at all?
3. Lipids
Lipids come from the Greek word lipos meaning fat. Lipids are family of biomolecules
group together because of its property of being hydrophobic (water- fearing). Lipids are nonpolar molecules making it soluble to non-polar solvents like acetone, ether and benzene. It
is classified into four categories: (1) triglycerides,
(2) Phospholipids, (3) Steroids.
Fatty acid
Fatty acid is a chain-like molecule containing a long chain of carboxylic acid. Fatty acid
can be saturated (contains single bonds) in its long chain hydrocarbon chain or unsaturated
(contains double bond). Since lipids are non-polar molecule, it is insoluble in water. Saturated
fatty acid is a straight chain where all the carbon atoms in the chain have two hydrogen singly
bonded to making the molecules to form a strong attraction. Because of this strong attraction,
saturated fatty acid have high melting point and are solid at room temperature Unsaturated
fatty acid on the other hand, tends to bend due to the presence of a double bond in one of the
carbon in the chain. The molecule will not be as close as that of the saturated fatty acid.
Unsaturated fatty acids have low melting points than saturated fatty acids.
21
Fig. 7. Fatty Acid
Retrieved: June 19, 2020 from https://dlc.dcccd.edu/biology1-3/lipids
Triglycerides
Are lipids that contain glycerol backbone and 3 fatty acids. The 3 fatty acids connected
to the glycerol backbone are not necessarily of the same kind.
Fat and oils are example of triglycerides. Fats are usually from animal sources contain
mostly saturated fatty acid making it solid at room temperature. Oil refers to a triglyceride from
plant sources. It contains unsaturated fatty acid and is liquid at room temperature.
Phospholipids
Is another type of lipids that contains glycerol, two fatty acids, and a phosphate group.
Phospholipids (Fig.8), unlike other kind of lipids, it has a polar end (hydrophilic end) which is
the phosphate group and non-polar end (hydrophobicend), the fatty acid group. The dual
property of liquid allows the phospholipid to forma bilayer.
22
Fig. 8. Phospholipid
Image retrieved: June 19, 2020 from
https://www.researchgate.net/figure/molec
ular-structure-of-phospholipid
Activity 4.
Study the structure of DNA and answer the questions below.
Fig. 9.DNA Structure.
Retrieved June 19, 2020 from https://ib.bioninja.com.au/standard-level/topic-2-molecularbiology/26-structure-of-dna-and-rna/dna-structure.html
1. What are the common parts of the nucleotide? _
_
_
2. Name the different kinds of nitrogenous bases found in the DNA molecule.
_
23
3. In DNA what is the paring arrangement of the bases?
_
_
_
4. Nucleic Acids
Nucleic acid is important macromolecules that serve as storage of genetic information
of the cell. It is made up of nucleotide monomers that contain a nitrogenous base, a pentose
sugar, and a phosphate group. DNA and RNA are the two types of nucleic acid with specific
functions.
DNA (deoxyribonucleic acid), the blueprint of life carries the genetic material and
provides information for its own replication. It is a double helix structure composed of a sugar
and phosphate backbone and complementary bases Adenine- Thymine and CytosineGuanine pair.
RNA (ribonucleic acid) on the other hand, carries the information from DNAfor
protein synthesis. There are three types of RNA namely:
1. Messenger RNA (mRNA)
2. Ribosomal RNA (rRNA)
3. Transfer RNA (tRNA)
Figure 9. Structure of Nucleic Acid
Retrieved June 19, 2020 from https://www.britannica.com/science/nucleic-acid
24
What’s More
Do this….
Matching Type: Match the structure in column A with the Macromolecules in column
B. Write the letter of your answer in your notebook.
COLUMN A
COLUMN B
1.
A. carbohydrates
2.
B. Lipids
Retrieved June 19, 2020 from https://rb.gy/s79lc0
3.
C. Nucleic Acid
4.
D. Proteins
25
What I Have Learned
Let’s summarize…..






Carbohydrates, Proteins, Lipids and Nucleic acid are the four classes of
macromolecules.
Carbohydrates composed mainly carbon, hydrogen and oxygen. It is
categorized as simple sugar (monosaccharides and disaccharides) and
complex sugar (polysaccharides). Glucose, Galactose and Fructose are
examples of monosaccharides. Disaccharides are carbohydrates
composed of 2 saccharides units and a polysaccharide with many
saccharide units. The saccharide units in disaccharides and
polysaccharides are bonded via glycosidic bond.
Proteins composed C, H, O, and N. Sulfur and other metals can also
be found in some proteins. Proteins as one of the macromolecules that
are made from multiple units of simple molecules called amino acids.
Collagen, Keratin, Hemoglobin, Myoglobin, and Fibroin are examples
of Proteins. It properties and function is determine by their structures.
Enzymes are also a kind of protein which catalyzes a reaction without
being used up.
Lipids are family of biomolecules group together because of its property
of being hydrophobic (water-fearing). Lipids are non-polar molecules
making it soluble to non-polar solvents like acetone, ether and benzene.
It is classified into four categories: (1) triglycerides, (2) Phospholipids,
(3) Steroids.
Nucleic Acid is important macromolecules that serve as storage of
genetic information of the cell. It is made up of nucleotide monomers that
contain a nitrogenous base, a pentose sugar, and a phosphate group.
DNA and RNA are the two types of nucleic acid with specific functions.
26
Assessment
Direction: Read each statement carefully. Write the letter of your answer in your
notebook.
1. The biological macromolecules composed of multiple units of amino acids is
A. Carbohydrates
C. Lipids
B. Proteins
D. Cellulose
2.
Which of the following sugars is a disaccharide?
A. Fructose C. Glucose
B. Galactose D. Sucrose
3. Carbohydrates contains the following elements EXCEPT
A. Carbon
C. Nitrogen
B. Hydrogen
D. Oxygen
4. Which of the following polysaccharide is found in the cell wall of plants?
A. Amylose
C. Cellulose
B. Amylopectin
D. Starch
5. A disaccharide which is mainly found in milk and other milk products is
A. Glucose
C. Maltose
B. Lactose
D. Sucrose
6. What macromolecule is represented in the figure below?
A. Carbohydrates
B. Lipids
C. Nucleic Acid
D. Proteins
7. Proteins found in hair, skin and nails is
A. Collagen
C. Keratin
B. Fibroin
D. Myoglobin
8. A type of protein which carries oxygen from the lungs to the bloodstream is
A. Collagen
C. Hemoglobin
B. Keratin
D. Myoglobin
9. A type of lipid which contain a hydrophilic end and a hydrophobic end is
A. Fatty acids
C. Phospholipids
B. Oils
D. Wax
27
10. In DNA, Thymine is paired with
A. Adenine
B. Cytosine
C. Guanine
D. Uracil
11. The following statement describes saturated fatty acid EXCEPT
A. It contains a carbon to carbon single bond.
B. It has high melting point.
C. It is solid at room temperature.
D. It contains a carbon to carbon double bond.
12. Amino acids in proteins are joined together by _
A. Glycosidic bond
C. Metallic bond
B. Hydrogen bond
D. Peptide bond
_
13. Which of the statements below DOES NOT describe an enzyme? Enzymes
A. are proteins
C. being used up during the reaction
B. catalyzes a reaction
D. speeds up a reaction
14. Deoxyribonucleic acid (DNA) carries genetic information of the cell. A DNA
molecule contains the following EXCEPT
A. Fatty acids
C. Pentose sugar
B. Nitrogen bases
D. Phosphate group
15. It contains an unsaturated fatty acid commonly found in plant and is liquid at
room temperature. This lipid being describe is
A. Fats
C. Steroids
B. Oils
D. Wax
28
Senior High School
Physical Science
Quarter 1-Module 3
Week 5: Collision Theory and the Factors
Affecting the Reaction Rate
Week 6: Limiting Reactant and Percent Yield
iii
TABLE OF CONTENTS
Page
What This Module is About
v
What I Need to Know
v
How to Learn from this Module
v
Icons of this Module
vi
What I Know
1
Lesson 1 – Collision Theory and Factors Affecting the Rate of Reaction
3
What’s In
What’s New:Effect of Surface Area/Particle Size of the Reactants
What is It
What’s New:Effect of Concentration on Reaction Rates
What is it
What’s New:Effect of Temperature on Reaction Rates
What is it
What’s New: Effect of Catalyst on Reaction Rates
What is it
What’s More: Identifying Scenarios
What’s More: Real-life Applications
What I Have Learned: True or False)
Lesson 2 – Limiting Reactants and Percent Yield
What I Need to Know
What’s In
What’s More: Solving Limiting Reactant Problems
What’s More: Solving Percent Yield Problems
What’s More: Why Percent Yield is Usually Less than 100%?
What I Have Learned
What I Can Do: Essay
Assessment
Key to Answers
References
3
4
5
6
7
7
8
9
9
10
11
11
12
12
13
15
17
18
18
19
20
22
23
iv
What This Module is About
This module discusses how the collision theory is used to explain the effectsof
concentration, temperature, particle size, and presence of catalyst on the reaction rate. The
limiting reactant and the amount of product that is formed in the chemical reaction are also
discussed. Understanding the concepts in this module will enable us to explain the chemical
changes that are happening around us in our daily lives.
The following are the lessons contained in this module
Lesson 1- The Collision Theory and the Factors Affecting Reaction Rate
Lesson 3- Limiting Reactant and Percent Yield
What I Need to Know
After going through this module, you are expected to:
1. Use simple collision theory to explain the effects of
concentration,temperature, and particle size on the rate of
reaction
(S11/12PS-IIIf-23)
2. Define catalyst and describe how it affects reaction
rate (S11/12PS-IIIf-24)
3. Calculate the percent yield of a reaction (S11/12PS-IIIh-26)
4. Determine the limiting reactant in a reaction and calculate the amount
of product formed (S11/12PS-IIIh-27)
How to Learn from this Module
To achieve the learning competencies cited above, you are to do thefollowing:
•
•
•
Take your time reading the lessons carefully.
Follow the directions and/or instructions in the activities and
exercisesdiligently.
Answer all the given tests and exercises.
v
Icons of this Module
vi
What I Know
MULTIPLE CHOICE
Directions: Read and understand each item and choose the letter of the correct answer.
Write your answers on a separate sheet of paper.
1. What do you call the minimum amount of energy needed to start a
chemical reaction?
A. Activation energy.
C. Reaction mechanism energy
B. Energy of the reaction.
D. The entropy of reaction
2. Which statement best describes the Collision theory?
A. All collisions lead to chemical reactions.
B. Most collisions lead to chemical reactions.
C. Very few reactions involve particle collisions.
D. Effective collisions lead to chemical reactions.
3. Which is/are necessary for successful collisions to occur?
I. Favorable collision geometry.
II. Sufficient kinetic energy.
III. Large change in enthalpy (∆H).
A. I only
C. II and III only
B. I and II only
D. I, II and III
4. Which of the following will decrease the number of effective collisions during a
chemical reaction?
A. Adding a catalyst.
C. Decreasing the temperature.
B. Increasing the surface area.
D. Increasing reactant concentrations.
5. Which of the following will increase the reaction rate?
A. Adding a catalyst
B. Decreasing temperature
C. Using lumps instead of powder
D. Decreasing the concentration of an acid
6. Crushing a solid into a powder will increase the reaction rate. Why?
A. The particles will collide with more energy.
B. The powdered form has more surface area.
C. The activation energy barrier will be lowered.
D. The orientation of colliding particles will be improved.
7. Why does increasing the temperature of the reactants increase the reaction rate?
A. Heat energy increases the size of the molecules of reactants, and therefore
the molecules react more frequently.
B. Heat energy helps to lower the amount of overall energy that is required for
the reaction to occur.
C. Heat energy causes some of the reactants to evaporate, thereby increasing
the concentration of the reactants.
D. Heat energy causes the particles of the reactants to move faster, therefore,
react with each other more frequently.
8. Enzymes are an important component in the human body. Most chemical reactions
do not occur or will proceed slowly without enzymes. What are enzymes?
A. Biological Catalyst
B. Simple elements
C. Chemicals that increase the surface area
D. Molecules used to increase concentration.
9. How does a catalyst makes a chemical reaction faster?
A. It makes lower energy pathways available.
B. It increases the concentration of products.
C. It increases the concentration of the reactants.
D. It binds to enzymes to release substrate.
10. What happens to a catalyst in a chemical reaction?
A. It evaporates.
B. It remains unchanged.
C. It is incorporated into the reactants.
D. It is incorporated into the products.
11. Which of the following substances act as catalysts in the body?
A. carbohydrates
B. lipids
C. nucleic acids
D. enzymes
12. What is a limiting reactant?
A. The reactant that makes the product.
B. The reactant that is fully consumed prevents more products from being made.
C. The reactant that is used up last and prevents more products from being
made.
D. The substance that is in excess that doesn't get used up as a reactant.
13. For the reaction: C5H12 + 8 O2 → 5 CO2 + 6 H2O
If 2 moles of C5H12 & 8 moles of O2 react, what is the limiting reactant?
A. C5H12
B. O2
C.
CO2
D.
H2O
14. Consider the reaction in # 13, how many moles of CO2 is produced in the
reaction?
A. 5
B. 6
C.7
D.8
15. What is the mass of hydrogen gas (H2) formed when 25 grams of aluminum reacts
with excess hydrochloric acid according to this balanced chemical equation:
2𝐴𝑙 + 6 𝐻𝐶𝑙 → 2𝐴𝑙𝐶𝑙3 + 3𝐻2
A. 0.41 g
B. 1.2 g
( 𝐻i𝑛𝑡:
C. 1.8 g
2
1
27
𝐴𝑙; 35𝐶𝑙;
1𝐻;
13
17
D. 2.8 g
)
Lesso
n1
Collision Theory and the Factors Affecting
Reaction Rate
What’s In
Chemical reactions are all around us. We witness it every day- combustion, digestion,
photosynthesis, cooking, and many more. Have you ever wondered what causes a chemical
reaction? What are needed for a chemical reaction to occur?
For this lesson, we will discuss the Collision Theory that provides a qualitative
explanation of chemical reactions and the rates at which they occur. It explains why some
chemical reactions are faster while others are slow.
This theory states that in order for a chemical reaction to occur, the reactant
particles (atoms or molecules) must effectively collide. Effective collision means that
reactants collide with each other with sufficient energy (known as the activation
energy) and proper orientation. The absence of any one of these factors will not
result in a chemical reaction.
The Collision Theory further tells us that the rate of a chemical reaction is proportional
to the number of successful collisions between the molecules of the reactants. The more often
reactant molecules collide effectively, the more often they react with one another and the
faster the reaction rate.
Activation Energy- the minimum amount of energy used to initiate a chemical reaction. If the
reactant particles do not possess the required activation energy when they collide, they simply
bounce off each other without reacting.
Figure 1. Combustion of LPG Gas- a chemical
reaction with a fast reaction rate.
3
Figure 2. Rusting of Iron- a chemical reaction
with a slow reaction rate.
Factors that Affect Reaction Rates
Chemical reactions proceed at different rates. Some reactions can happen at very fast
rates like the combustion of LPG gas in kitchens, while others may occur at a slower rate over
several years like the rusting of iron.
There are four (4) factors that affect the speed of a chemical reaction. These
are the (1) surface area/particle size of the reactants, (2) concentration of the
reactants, (3) temperature, and (4) the presence of catalysts. The collision theory
is used to explain the effects of these factors on the reaction rate.
We shall investigate the effects of these factors through activities. These activities
mostly use household materials so that students will be able to perform them at home.
1. Effect of Surface Area/Particle Size of the Reactants on Reaction Rates
Let us determine the effect of the surface area/ particle size of the reactants tothe
reaction rate by doing Activity 3.1.1
What’s New
Activity 3.1.1.The Effect of Surface Area/ Particle Size on Reaction Rates
Objective: Investigate the effect of concentration on the rate of a reaction.
Materials:
2 Similar cups
2 effervescent tablets ((E.q. Alka seltzer tablets, Berocca, Panadol, Redoxan) Mortar
and pestle
Stopwatch
Procedure:
Part A. Whole Tablet
1. Fill one cup with 100 mL of room temperature water.
2. Drop one (1) whole effervescent tablet into the cup of water. Record the time
theeffervescent tablet completely dissolves. Record data in Table 3.1.1.
Part B: Powdered Tablet
1.
2.
3.
4.
Place one (1) effervescent tablet into a mortar and grind to a fine powder.
Transfer the powdered tablet into a container.
Fill one cup with 100 mL of room temperature water.
Put the powdered tablet in the cup of water. Record the time the
effervescenttablet completely dissolves. Record data in Table 3.1.1.
4
Table 3.1.1: The Effect of Surface Area/ Particle Size on Reaction Rates
Reaction Condition
Time the tablet was fully
dissolved
Observations
Whole effervescent tablet
in a cup of water
powdered effervescent
tablet in a cup of water
Guide Questions:
1. Which reaction is faster? Why?
Answer:
_
_
___
2. How does the surface area/ particle size affect the reaction rate?
Answer:
_
_
What is It
In Activity 3.1.1, we used various particle sizes to compare the rates of reaction. You
observed that the powdered effervescent tablet dissolves faster in a cup ofwater than
the whole tablet. Why? Although they have the same mass, they differ insurface area.
Breaking the reactant into smaller pieces increases its surface areaallowing more
particles to be available for a collision.
In collision theory, as more particles collide the frequency of collision also increases
and more likely results to a faster reaction rate. The reaction becomes faster as particles get
smaller.
5
2. Effect of Concentration on Reaction Rates
The concentration tells us how much solute there is in a solution. Activity 3.1.2will
help us determine its effect on the reaction rate.
What’s New
Activity 3.1.2: Effect of Concentration on Reaction Rates
Objective: to investigate the effect of concentration on the rate of a
reaction.
Materials:
2 similar cups
1.5 mL of Water
6 mL pure Vinegar
2 spoonful of Baking soda
Procedure:
1. In one cup, use pure vinegar (3mL) and place one spoonful of baking soda.
Record in Table 3.1.2 the time it takes for the reaction to happen.
2. In another cup, add pure vinegar (1.5mL) and water (1.5 mL) before you add
the spoon full of baking soda. Record reaction time in Table3.1.2.
Table 3.1.2: Effect of Concentration on Reaction Rates
Concentration
Total Time of Reaction
Observations
Pure Vinegar
50% vinegar + 50% water
Guide Questions
1. Which reaction had the fastest rate? Why?
Answer:
_
_
2. Explain what could be occurring at the molecular level in each example. (How
are the molecules moving or acting?)
Answer:
_
_
__
3. Why substances with high concentrations react faster than substances with
low concentrations?
Answer:
_
6
_
What is It
In Activity 3.1.2, the pure vinegar has more concentration than the vinegar
solution which makes the reaction rate faster. The rates of many reactions depend
on the concentrations of the reactants. Reaction rates usually increase when the
concentration of one or more of the reactants increases. Increasing the
concentration means more reactant particles are in a given space (volume) which
increases the likelihood of collisions between them. The increased frequency of
collisions results in a faster reaction rate.
For a chemical reaction to occur, a certain number of energized molecules
must be equal to or greater than the activation energy. As the concentration
increases, the number of molecules with the minimum energy required also
increases, and thus the reaction rate increases.
3. Effect of Temperature on Reaction Rates
Temperature is the measure of the degree of hotness or coldness of anobject. It is a
measure of the average kinetic energy of the particles in an object. What is its effect on the
reaction rates? Let us find out in Activity 3.1.3.
What’s New
Activity 3.1.3: The Effect of Temperature on Reaction Rates
Objective:
1. To investigate the effect of temperature on reaction rates
Materials:
Hot water
Cold water
2 clear similar glasses
Stopwatch/Timer
Effervescent tablet (E.q. Alka seltzer tablets, Berocca, Panadol, Redoxan)
Procedure:
Part A: Hot Water
1. Fill a clear glass with exactly 100 mL of hot water.
2. Take the temperature of the hot water by using a laboratory thermometer andrecord
your data in Table 3.1.3.
3. Drop 1 effervescent tablet into the hot water. Measure the time it takes for thetablet
to fully dissolve. Record your data in Table 3.1.3.
Part B. Cold Water
1. Fill a clear glass with exactly 100 mL of cold water.
Use the thermometer to take the temperature of the cold water and record it in Table3.1.3.
2. Drop 1 effervescent tablet into the cold water. Measure the time it takes for thetablet
to fully dissolve. Record your data in Table 3.1.3.
7
Table 3.1.3: The Effect of Temperature on Reaction Rates
Temperature
of water
Time the tablet was
fully dissolved
Observations
Hot water
Cold water
Guide Questions:
1. In which glass of water does the effervescent tablet dissolved faster? Why?
Answer:
_
_
2. What happens to the reactant molecules as you increase the temperature
of the reaction?
Answer:
_
_
_
_
3. How does the temperature affect the reaction rate?
Answer:
_
_
What is It
The effervescent tablet dissolved faster in hot water than in cold water. Therefore, the
reaction rate is directly proportional to the temperature. The reaction becomes faster as the
temperature gets higher.
Increasing the temperature of the reactants increases the kinetic energy that it
possesses causing the particles to move faster. As they move faster, the frequencyof collision
between them increases. This gives the reactants enough energy to overcome the activation
energy thus making the reaction faster.
8
4. Effect of a Catalyst on Reaction Rates
What’s New
Activity 3.1.4: Effect of a Catalyst on Reaction Rates
Objective:
1. to investigate the effect of a catalyst on reaction rate
Materials:
Hot water
2 Test tubes
Hydrogen peroxide (H2O2)
Manganese dioxide
Procedure:
1. Place 10mL of hydrogen peroxide (H2O2) in 2 separate test tubes. Place onetest
tube in a hot water bath. Note the rate bubbles form.
2. Add a pinch of manganese dioxide in the second test tube. Note the rate
bubbles form.
Guide Questions:
1. How will you compare the rate at which bubbles were produced?
Answer:
_
_
2. What happened to the test tube added with manganese dioxide? What do
you call the manganese dioxide?
Answer:
_
_
_
3. What is a catalyst? How does it affect the reaction rate?
Answer:
_
_
_
What is It
In Activity 3.1.4, manganese dioxide catalyzes the reaction. A catalyst is a
substance that speeds up the rate of a chemical reaction without itself being consumed by
the reaction. Once the reaction is over, you'd have exactly the same amount of catalyst as
you did at the start.
The addition of a catalyst provides a new reaction pathway that offers a
lower activation energy. Lowering the activation energy enables more reactant molecules to
collide with enough energy to overcome the smaller energy barrier.
Enzymes are proteins that act as catalysts for biochemical reactions.
9
Table 3.1.5 Examples of Enzymes
Enzyme
CARBOHYDRATE
DIGESTION
Salivary amylase
Pancreatic amylase
Maltase
Lactase
PROTEIN DIGESTION
Pepsin
Trypsin
peptidases
NUCLEIC ACID
DIGESTION
Nuclease
Nucleosidases
Produced
by
Site of
Action
Optimum
pH
Digestion
Salivary glands
Pancreas
Small Intestine
Small Intestine
Mouth
Small Intestine
Small Intestine
Small Intestine
Neutral
Basic
Basic
Basic
Starch+ H2O→maltose
Starch+ H2O→maltose
Maltose+ H2O→glucose+ glucose
Lactose+ H2O→glucose+
galactose
Gastric Glands
Pancreas
Small Intestine
Stomach
Small Intestine
Small Intestine
Acidic
Basic
Basic
Protein+ H2O→peptides
Protein+ H2O→peptides
peptide+ H2O→amino acids
Pancreas
Small Intestine
Small Intestine
Small Intestine
Basic
Basic
RNA and DNA +H2O→nucleotides
Nucleotide + H2O→ base+
sugar+phosphate
Pancreas
Small Intestine
Basic
Fat droplet + H2O→
monoglycerides+ fatty acids
FAT DIGESTION
Lipase
What’s More
Activity 3.2.1
Identifying the Scenarios
Identify whether the following scenarios will increase or decrease the reactionrate.
Write your answer on the space provided before each number.
_1. Breaking a reactant into smaller pieces.
_2. Increasing the temperature.
_3. Putting foods on the fridge.
_4. Diluting solutions.
_5. Adding heat.
10
What’s More
Activity 3.2.2
Real Life Applications
Which factor affecting reaction rate is depicted in each of the following
situation/scenario. Write your answers in the second column of the table below.
Situation/Scenario
1. Protein is broken down in the stomach by the
enzyme pepsin.
2. More bubbles appear when a concentrated
solution of hydrochloric acid is added to a
magnesium strip than when a dilute solution of
the acid is added.
3. Raw potatoes are cut into thin slices for
cooking.
4. Blowing air on a campfire to help get it
going.
5. Grains of sugar dissolves quickly in water.
6. Smaller pieces of charcoal are used to grill
food.
7. Meat is stored in a refrigerator to last longer.
8. Acid rain erodes marble faster.
9. Protease is used to tenderize meat.
10. Leaving a glass of milk on the table causes it
to spoil easily.
Factor Affecting Reaction Rate
What I Have Learned
TRUE or FALSE: Write T if the statement is true and write F when it is false. Writeyour
answer before each number.
1. Collision theory states that particles have to collide with sufficient
energy to react.
2. Starter energy is the minimum amount of energy required for a
successful collision.
3. Adding heat will increase the reaction rate.
4. Grains of sugar has a greater surface area than a cube of
sugar of the same mass.
5. Usually lowering the temperature will slow down a reaction.
11
Lesson
2
Limiting Reactant and Percent Yield
What I Need to Know
In the previous lesson, you were able to understand how a chemical reaction occurs
and what happens in a chemical change. You were able to realize that for a chemical reaction
to happen, the reactant particles must collide with enough energy and proper orientation. You
also learned that chemical reactions speed up or slow down by the four factors affecting
reaction rate.
Aside from knowing those concepts, you must also know what limits a chemical
reaction, when a chemical reaction stops and how much product forms after a chemical
reaction. In this lesson, you will know how to determine the limiting reactant and how to
compute for the percent yield.
At the end of this lesson, you are expected to:
1. Explain the concept of limiting reactant, excess reactant, theoretical
yield, actual yield and percent yield.
2. Identify the limiting reactant in the chemical reaction.
3. Identify the excess reactant in the chemical reaction,
4. Solve for the amount of product formed after the reaction.
5. Compute for the percent yield.
12
What’s In
In your lower grades, you dealt with ideal Stoichiometry calculations where reactants
combine with one another in a specific molar ratio described by the balanced equation. In that
case, you assumed that all the reactants are consumed in the reaction and are completely
converted into products. However, in most chemical reactions, reactants are present in mole
ratios that are not the same as the ratio ofthe coefficients in the balanced chemical equation.
The quantities of reactants are rarely exact. Usually there is too much of one reactant, and not
enough of another. Therefore, not all reactants are completely converted into products. One
reactant is completely consumed in the reaction while the other one is in excess.
Limiting Reactant
The limiting reactant is the reactant that is completely used-up or consumed in a
chemical reaction. It is called the limiting reactant because it limits the amount of product
formed in the reaction. Once it is consumed, the reaction stops.
Excess Reactant
The excess reactant is the reactant other than the limiting reactant. It is thereactant that is
left-over after chemical reaction.
How to Find the Limiting Reactant?
How can you determine which reactant is limited? Consider the reaction between
molten sulfur (S8) and chlorine gas (Cl2) to form disulfur dichloride according to this equation:
S8 (l)+ 4 Cl2 (g)→ 4 S2Cl2 (l)
If 200.0 g of sulfur reacts with 100 g chlorine, what is the limiting reactant?
What mass of disulfur dichloride is produced?
This kind of problem is an example of a limiting reactant problem since youare
given the quantities of both the reactants and you are asked to calculate for the amount of the
product. To solve limiting reactant problems, consider the following steps:
Step 1: Write down the known and the unknown quantities in the problem.
Given: mass sulfur = 200.0 g
mass chlorine= 100 g
Unknown: a.) limiting reactant
b.) mass of disulfur dichloride (S2Cl2)
Step 2: Balance the chemical equation.
In the problem, the chemical equation is already balanced.
13
Step 3: Convert mass of reactants to moles.
Use the molar mass ( inverse ) as a conversion factor
Step 4: Calculate the mole ratio of the reactants.
To determine the actual ratio of moles, divide the available moles of chlorine bythe
available moles of sulfur which you calculated in Step 3.
Actual
Ratio
To get the stoichiometric ratio, divide the moles of chlorine to the moles ofsulfur
from the balanced chemical equation.
S8 (l)+ 4 Cl2 (g)→ 4 S2Cl2 (l)
𝑆𝑡𝑜i𝑐ℎi𝑜𝑚𝑒𝑡𝑟i𝑐 𝑟𝑎𝑡i𝑜 = 4 𝑚𝑜𝑙𝑒𝑠 𝐶𝑙2
1 𝑚𝑜𝑙𝑒 𝑆8
Step 5: Compare the actual ratio to the stoichiometric ratio
The actual ratio tells us that we need 1.808 mole of Cl2 for every mole of S8. In the
stoichiometric ratio, 4 moles of Cl2 is needed for every mole of S8. Since only1.808 moles of
chlorine is actually available for every 1 mole of sulfur instead of the 4 mole of chlorine required
by the balanced chemical equation then chlorine is the limiting reactant.
How to Get the Amount of Product Formed?
Use the calculated amount of moles of the limiting reactant to determine the moles of
product formed. Then, convert the number of moles of product to its mass.
Going back to the problem, we are asked of the mass of disulfur dichloride produced
in the reaction. To calculate:
mole vale of
the limiting
reactant
x
mole ratio of the
limiting reactant
and the product
x
molar mass of
the product
=
Mass of the
Product
Now you know that 190.4 g of S2Cl2 is produced when 1.410 mol Cl2 reacts
with an excess of S8. ( Note: This is the theoretical yield)
14
How to get the Excess Reactant?
What about the reactant sulfur, which you know is in excess? How much of it actually
reacted? You can calculate the mass of sulfur needed to react completely with 1.410 mol of
chlorine using a mole-to- mass calculation. The first step is to multiply the moles of chlorine
by the mole ratio of sulfur to chlorine to obtain the number of moles of sulfur. Remember, the
unknown is the numerator and the known in the denominator.
Now, to obtain the mass of sulfur needed, 0.3525 mol S8 is multiplied by theconversion factor
that relates mass and moles, molar mass.
Knowing that 90.42 g S8 is needed, you can calculate the amount of sulfur leftunreacted
when the reaction ends. Since 200.0 g of sulfur is available and only
90.42 g of sulphur is required, the excess mass is:
200.0 g S8(g) available − 90.42 g S8(g) needed = 109.6 g S8(g) in excess.
What’s More
Solving Limiting Reactant Problems
Instruction: Show your complete solutions legibly in one (1) whole sheet of paper.(Total
Score: 25 points)
1. Given the following reaction:
Mg (OH)2+2 HCl →Mg Cl2+2 H2O
If 16.0 g of Mg (OH)2 and 11.0 g of HCl are combined.
a. What is the limiting reactant? ( 5 points)
b. How many grams of Mg Cl2 + will be produced? ( 5 points)
2. The reaction between solid white phosphorus and oxygen produces solid
tetraphosphorusdecoxide (P4O10).
a. Write the balanced chemical equation of the reaction. ( 5 points)
b. Determine the mass of tetraphosphorusdecoxide (P4O10) formed if 25.0
phosphorus (P4) and 50.0 g of oxygen (O2) are combined. ( 5 points)
g of
c. How much of the excess reactant remains after the reaction stops? (5 points)
15
How to get the Percent Yield?
Chemical reactions don’t always give us the exact amount of product we are expecting.
Usually, we yield amount of product that is less than our expected outcome. To determine
how much product we obtained, we get the percent yield.
In many calculations you have been practicing, you have been asked tocalculate the
amount of product that can be produced from a given amount ofreactant. The answer you
obtained is called the theoretical yield of the reaction. The theoretical yield is the maximum
quantity of a product derived from a given quantity of reactant. The actual yield is the amount
of a product produced when an experiment is performed. Hence, the percent yield of product
is the ratio of the actual yield ( amount of a product from the experiment) to the theoretical
yield expressed as a percent. It effectively states how much of the reactants become product
in a chemical reaction.
Sample Problem1:
The decomposition of magnesium carbonate forms 15 grams of magnesium oxide
(MgO) in an experiment based on this equation:
MgCO3 → MgO + CO2
The theoretical yield is 19 grams. What is the percent yield of magnesium oxide?
Solution:
Given: actual yield=15 g MgO
theoretical yield = 19 g MgO
Unknown: % Yield
Solution:
% 𝑦i𝑒𝑙𝑑 =
15 g 𝑀g0
𝑥 100
%𝑦i𝑒𝑙𝑑 = 79%
16
Sample Problem 2:
What is the percent yield of sodium sulfate when 32.18 g of sulfuric acidreacts
with excess sodium hydroxide to produce 37.91 g of sodium sulfate?
Solution:
Given: 𝑚𝑎𝑠𝑠 𝐻2𝑆𝑂4 = 32.18 𝑔
𝑚𝑎𝑠𝑠 𝑁𝑎2𝑆𝑂4 (𝑎𝑐𝑡𝑢𝑎𝑙 𝑦i𝑒𝑙𝑑) = 37.91 𝑔
In the problem, it is clearly stated that sodium hydroxide is the excess reactant.
Therefore, sulphuric acid is the limiting reactant. Use the limiting reactant toget the theoretical
yield of sodium sulphate.
The theoretical yield is 46. 59 g 𝑁𝑎2𝑆𝑂4
% 𝑦i𝑒𝑙𝑑 =
37.91 𝑔 𝑁𝑎2𝑆𝑂4
46.59 𝑔 𝑁𝑎2𝑆𝑂4
𝑥 100 = 81.37 %
Therefore, the percent yield is 81.37%
What’s More
Solving Percent Yield Problem
Instruction: Show your complete solutions legibly in a one (1) whole sheet of paper.(Total
Score:10 points)
1. When potassium dichromate (K2CrO4) is added to a solution containing
0.500 g silver nitrate (AgNO3), solid silver chromate (Ag2CrO4) is formed.
( Note: Be sure to write down the balanced chemical equation.)
a) Determine the theoretical yield of the silver chromate precipitate.
(5 points)
b) If 0.455 g of silver chromate is obtained, calculate the percentage yield.
( 5 points)
17
What’s More
Why Percent Yield is Usually Less than 100%?
List down four (4) possible reasons why percent yield is usually less than 100%.
1.
_
2.
__
_
_
__
_
_
__
_
_
_
3.
_
4.
_
__
__
_
_
What I Have Learned

The theoretical yield is the maximum quantity of product derived from a given
quantity of reactant. It is calculated from the balanced chemical equation.
 The actual yield is the amount of product actually produced when an
experiment is performed.
 Percent yield is the ratio of actual yield to theoretical yield expressed
as percent.
 The limiting reactant is the reactant that is completely consumed during a
chemical reaction. Reactant that remain after the reaction stops are called
excess reactants.
Percent yield is determine by this formula:
18
What I Can Do
Essay: Write a minimum of 100 words essay on the topic presentedbelow.
Question: How can an understanding of the limiting reactant, excess reactantand
percent yield help manufacturing companies?
_
_
_
_
_
_
_
__
_
_
_
_
_
_
_
_
19
Assessment
MULTIPLE CHOICE
Directions: Read and understand each item and choose the letter of the correct
answer. Write your answers on a separate sheet of paper.
1.
What is the effect of temperature rise on reaction rate?
A. It increases molecular concentration and slows reaction rate.
B. It increases the number of effective collisions among reactants, thus
increasing the reaction rate.
C. It decreases the system's energy and limits how much further reaction can
take place.
D. It decreases the number of collisions and the energy of molecules to limit
further reaction.
2. Your Science teacher demonstrates an interesting chemical reaction in your class.
The teacher dissolves zinc strips in a container with concentrated hydrochloric
acid. The teacher then added more hydrochloric acid in the container and added
more pieces of zinc strips. What factor will NOT affect the reaction rate?
A. The amount of hydrochloric acid.
C. The concentration of reactants.
B. The surface area of the Zinc.
D. The size of the container.
3. When the concentration of reactant molecules increases, the rate of reaction
increases. What is the best explanation for this? As the reactant concentration
increases,
A. the rate constant increases.
B. the activation energy increases.
C. the average kinetic energy of molecules increases.
D. the frequency of molecular collisions increases.
4. What does a catalyst do?
A. Stabilises a reaction
B. Cools the reaction down
C. Increases the rate of reaction
D. Increases the concentration of the reaction
5. It helps to speed up a reaction but does not take part in the chemical reaction.
A. Catalyst
B. Coefficient
C. Combustion
D. Reactants
6. Which among these conditions will increase the rate of a chemical reaction?
A. Increased temperature and decreased concentration of reactants.
B. Increased temperature and increased concentration of reactants.
C. Decreased temperature and decreased concentration of reactants.
D. Decreased temperature and increased concentration of reactants.
7. Grinding a seltzer tablet into powder increases the rate of reaction due to
increased
A. Concentration
B. Reactants
C. Surface area
D. Temperature
20
8. Why are many types of foods stored in refrigerators?
A. At lower temperature, the chemical reactions that spoil food occur slower
than usual.
B. Refrigerators also contain enzymes that slow the rate of reactions that spoil
the food.
C. The volume inside the refrigerator decreases the concentration of the food
particles, allowing them to decompose more slowly.
D. Bacteria do not grow well in dark places.
9. Which reactant controls the amount of product formed in a chemical reaction?
A. Composition
B. Excess
C. Limiting
D. Mole
10. The
yield is the maximum amount of product possible in a
reaction. This determines the amount of product that should be produced in a
perfect setting.
A. Actual
B. Percent
C. Stoichiometry D. Theoretical
11. In a laboratory experiment, the sodium (Na) metal was reacted with chlorine gas
(Cl2), and the observed actual yield was 13.0 grams. What is the percent yield if
the calculated theoretical is 12.5 grams?
A. 100%
B. 104%
C. 96%
D.1.04%
12. Which of the following statements is most useful in determining the limiting
reactant in a chemical reaction.
A. Calculate the bond energies.
B. Determine the molar mass of the products.
C. Determine the masses of 100 mol of each reactant.
D. Calculate the mass of a single product formed from each reactant.
13. What amount of the excess reagent remains when 6.00 g of CS gas react with
10.0 g of Cl2 gas in this reaction?
3𝐶𝑙2(g) + 𝐶𝑆2(g) → 𝑆2𝐶𝑙2(𝑙) + 𝐶𝐶𝑙4
(Hint:12𝐶,
6
A. 2.42 g
B. 2.77 g
C. 3.58 g
35𝐶𝑙, 32𝑆)
17
16
D. 4.00 g
14. If 25.0 grams of Zn are reacted with 17.5 g of HCl according to65this equation:
1
35
𝑍𝑛 + 2𝐻𝐶𝑙 → 𝑍𝑛𝐶𝑙2 + 𝐻2
How many grams of H2 will be produced?
21
(Hint: 𝑍𝑛, 𝐻,
30
1
𝐶𝑙)
17
A. 0.382 g
B. 0.479 g
C. 0.765 g
D. 25.0 g
15. In the reaction below, 8.0 g of H2 react with 9.0 g of O2. Which of
the following statements is true?
2 H2 + O2
2 H2O
(Hint:16𝑂, 1𝐻 )
8
A. The equation is not balanced.
B. The H2 is the limiting reactant.
C. The O2 is the limiting reactant.
D. 2.0 moles of H2O would be produced.
22
1
Senior High School
Physical Science
Quarter 1 - Module 4
Sources of Energy
Ingredients of Cleaning Products
23
Table of Contents
What This Module is About ....................................................................................................... i
What I Need to Know................................................................................................................ i
How to Learn from this Module ................................................................................................ ii
Icons of this Module................................................................................................................. ii
What I Know ........................................................................................................................... iii
Lesson 4.1:
Sources of Energy ........................................................................... 1
What I Need to Know ........................................................................................ 1
What’s New: Match Me ..................................................................................... 1
What Is It: Energy Definition and Sources ......................................................... 2
What’s More: Tell Me ........................................................................................ 3
What’s More: Guess the Picture ....................................................................... 4
What I Have Learned: Imagine and Draw ......................................................... 5
What I Can Do: Choosing Energy ..................................................................... 5
Lesson 4.2:
Active Ingredients of Cleaning Products ....................................... 5
What’s In ........................................................................................................................ 5
What I Need to Know ........................................................................................ 6
What’s New: Word Twist.............................................................................................. 6
What Is It: Cleaning Agents ............................................................................... 6
What’s More: Word Search .......................................................................................... 9
What’s More: True or False ............................................................................... 9
What’s More: Crossword Puzzle ................................................................................. 9
What I Have Learned: Sum It Up .................................................................... 10
What I Can Do: Find Me ................................................................................. 11
Lesson 4.3:
Use of the Other Ingredients in Cleaning Agents ........................ 11
What’s In ...................................................................................................................... 11
What I Need to Know ...................................................................................... 12
What’s New: Detergent Action ................................................................................. 12
What Is It: Role of other Ingredients ................................................................ 12
What’s More: Fill Me In ................................................................................... 14
What’s More: Essay.................................................................................................... 14
What I Have Learned: Remember Me............................................................. 15
What I Can Do: Inventory Making ................................................................ 15
24
2
Summary ............................................................................................................................ 16
Assessment: (Post-Test) .................................................................................................... 17
Key to Answers .................................................................................................................. 19
Reference........................................................................................................................... 22
25
What This Module is About
This module discusses the sources of energy and the contribution of chemistry to the
understanding of household cleaning products.
This module has 3 lessons:
Lesson 1- Sources of Energy
Lesson 2-Active Ingredients of Cleaning Materials
Lesson 3-Use of the Other Ingredients in Cleaning Agents
Here, we are going to discuss the most common sources of the energy that our
community uses in our daily lives. After that, we are going to learn the active ingredients of
some of the most common cleaning products and the other uses of these active ingredients.
Have fun learning!
What I Need to Know
After going through this module, you are expected to;
1. Describe how energy is harnessed from different sources: fossil fuels; biogas;
geothermal; hydrothermal; batteries; solar cells; biomass (S11/12PS-IIIi-29)
2. Identify the active ingredients of cleaning products at home (S11/12PS-IIIi-j-31)
3. Give the use of the other ingredients in cleaning agents (S11/12PS-IIIi-j-32)
How to Learn from this Module
To achieve the objectives cited above, you are to do the following:
• Take your time reading the lessons carefully.
• Follow the directions and/or instructions in the activities and exercises diligently.
• You are expected to answer and complete the activities given in each lesson.
Carefully follow the instructions in each activity.
iii
Icons of this Module
What I Need to
Know
This part contains learning objectives that
are set for you to learn as you go along the
module.
What I know
This is an assessment as to your level of
knowledge to the subject matter at hand,
meant specifically to gauge prior related
knowledge
What’s In
This part connects previous lesson with that
of the current one.
What’s New
An introduction of the new lesson through
various activities, before it will be presented
to you
What is It
These are discussions of the activities as a
way to deepen your discovery and understanding of the concept.
What’s More
These are follow-up activities that are intended for you to practice further in order to
master the competencies.
What I Have
Activities designed to process what you
Learned
have learned from the lesson
What I can do
These are tasks that are designed to showcase your skills and knowledge gained, and
applied into real-life concerns and situations.
iv
What I Know
Multiple Choice: Write the letter of the best answer on your answer sheet.
1. What do you call the capacity to do work?
A. Acceleration
B. Bonding
C. Energy
D. Force
2. What is the ultimate source of energy?
A. Earth
B. Sun
C. Water
D. Wind
3. What is the energy that can be repeatedly used without being depleted?
A. Eternal
B. Non-renewable
C. Renewable
D. Unlimited
4. What do you call the energy that are available in limited supplies and eventually will be
depleted?
A. Eternal
B. Non-renewable
C. Renewable
D. Unlimited
5. What product is developed to facilitate the removal of dust and dirt and for disinfection?
A. Chemical
B. Cleaning Product
B. C. Collagen
D. Lotion
6. Which among the choices states that energy cannot be created nor destroyed, only
converted?
A. First law of Newton
B. First law of Thermodynamics
B. First law of the Universe
C. None of the above
7. What type of renewable energy comes from building dams on rivers?
A. Biomass
B. Hydrothermal energy
C. Solar energy
D. Wind energy
8. Which of the following is the most common and frequently used as a cleaning agent?
A. Chemicals
B. Chlorine
B. C. Shampoo
D. Water
9. What cleaning agent helps to stop the smell and stains caused by bacteria?
A. Detergent
B. Degreaser
B. C. Disinfectant
D. Water
10. What is formulated to aid in cleaning, making the task easier and faster to be done?
A. Cleaning agents
B. House maid
v
B. C. Personal Care Products
D. Vacuu
11. What cleaning agent is used in cleaning to destroy bacteria and viruses?
A. Acid
B. Degreasers
C. Disinfectant
D. Water
12. What active ingredient plays the key role of cleaning the materials to prevent diseases
brought by bacteria and viruses?
A. Antimicrobial Agent
B. Bleach Activators
C. Colorant
D. Enzymes
13. What substance contains a blue dye or pigment that provides bluing effect when
added to laundry products?
A. Bulking agents
B. Colorants
C. Flavors
D. Fragrances
14. How does the enzyme improve the quality of a paper sheet?
A. It makes it whiter
B. It makes it more writable
C. It makes it stronger and thicker D. It makes the paper colorful
15. What substance is commonly used as sugar-substitute?
A. Glucose
B. White Sugar
C. Flavor and sweetener
D. Sugarcane
vi
Lesson
Sources of Energy
1
What I Need to Know
This module discusses about the sources of energy and how the energy is
harnessed.
After going through this module, you are expected to describe how energy is
harnessed from different sources: fossil fuels; biogas; geothermal; hydrothermal; batteries;
solar cells; biomass.
What’s New
Activity 4.1.1 Match Me
Choose the answer that best matches the definitions below. Write the letter of your
answer on the column entitled “Match”.
Definition
1
2
3
4
5
Match
The ability to do work.
Key Terms
A. Chemical
Radios, vocal chords, and guitars
all produce this kind of energy.
Examples of this energy includes
computer screens, lamps, and the
sun.
The energy stored on the
chemical bonds of molecules,
which is released during a
chemical reaction.
.
The energy released when the
nucleolus of an atom is split
B. Energy
C. Light
D. Mechanical
E. Nuclear
F. Sound
1
What Is It
Defining energy is both simple and complicated. The definition varies from one field of
science to another, but the most common definition it uses is the ability to do work. Energy
can be found in almost everything and everywhere. Can it be found on the places we used to
go? Can we find it on the things we possess? The answer to that is yes! For example, when
we digest food, our body uses (chemical) energy embodied in the food to move around. When
we turn on the TV or gadgets, electricity is used to create the picture on the screen and the
sound it produces. Most of the electricity that we use in our daily lives are produced from the
chemical energy released in the burning of coal, oil or gas. Now, if energy can be found literally
on everything, why do we hear so much about energy crisis? According to the First Law of
thermodynamics, also known as the Law of Conservation of Energy, energy can neither be
created nor destroyed; energy can only be transferred or changed from one form to another 1.
If that is the case, then there is no need to worry about running out of energy?
Well, that question can be answered if we fully understood the concept of energy. As
stated above, energy comes in different forms and can be used in different ways through
conversion. Given a scenario of leaving a hot milk in an airconditioned room, what will happen
to the milk? In a matter of time, the hot milk will turn into a cold milk, thus, there is heat loss.
Is there a way of turning back the milk into hot once it has cooled down? Is there any way to
collect the heat loss from the milk to the environment? None. In any example that we consider,
we will see that energy, in the usable form, is dissipated to the surroundings in less usable
forms. Hence, energy is consumed and would not replenish once it’s used to do work. With
this taken into consideration, the next thing to do is look for conventional and renewable
sources of energy.
Conventional energy sources are the oldest sources of energy like coal and petroleum.
Conventional energy sources are limited. They will not last forever and will eventually run out.
Renewable energy, on the other hand, uses energy sources that are continually replenished
by nature—the sun, the wind, water, the Earth’s heat, and plants. With the use of renewable
energy technologies these fuels are turned into usable forms of energy—regularly electricity,
but also heat, chemicals, or mechanical power. To put it simply, this energy can be used again
and again and will never run out.
The following are the energy sources:
A. Fossil Fuels: Fossil fuels comes from organic remains of prehistoric organisms, example
of this are hydrocarbons such as oil, coal, and natural gas. Coal is the world’s
largest source of fossil fuel. It is comparably affordable and is readily
obtainable. Fossil fuels harnessed energy from the sun when they were still
alive through the process of photosynthesis. To put it simply, fossil fuels are
captured sunlight!
B. Biogas: This kind of energy can be produced from raw materials such as agricultural waste,
manure, municipal waste, plant material, sewage, green waste or food waste.
Biogas is a renewable energy source.
2
C. Geothermal: This energy optimizes the heat energy from the earth’s crust. This heat
energy heats up rocks affecting the nearby groundwater. Once the
groundwater becomes so hot, it turns into an underground steam, then this
steam is used to drive turbines that generate electricity. It is said that
geothermal energy is the main source of energy in the Visayas region.
D. Hydro Power Plant: Hydrothermal energy is usually associated with dams since there is
only few waterfalls exist in the country. The kinetic energy and
potential energy of a falling water is being converted to produce
electricity. This is the main source of electricity in Mindanao.
E. Batteries: It is a chemical source of energy that produces direct current, DC. Some are
rechargeable; some are not.
F. Solar Cells: The energy derived from the sun through the form of solar radiation is directly
converted into electricity. This energy will continue to renew until the sun
cease to exist. Solar cells system mostly has these three main parts; 1.
modules that convert sunlight into electricity; 2. Inverters where electricity is
being converted into alternating current so it can be used by most household
appliances; 3. battery that store the excess electricity produced by the system.
G. Biomass: It refers to the organic matters and waste from plants and animals such as
compost, crop remnants and garbage. Plants get the energy from the sun
through the process of photosynthesis and this energy is passed to animals
upon consumption. Biomass is used to produce alcohol and methane which
are fuels useful in energy manufacture and running cars.
H. Thermal Power Plant: Heat energy is being produced and converted into electricity by
burning large amount of fossil fuels are burnt in power stations.
I. Wind Power: The energy from the wind is being harnessed by the wind turbines, converting
the wind energy into mechanical energy. This kind of energy is renewable
since the wind on the surroundings is unlimited.
What’s More
Activity 4.1.2
A. Tell Me
Provide the answers for the following questions. You may use different materials as a
reference for the articulation of your points.
1. What is a good fuel?
2. If you could use any source of energy for heating your food, which one would you use and
why?
3
3. Why are we looking at alternate sources of energy?
4. What are the disadvantages of fossil fuels?
5. Can any source of energy be pollution-free? Why or why not?
B. Guess the Picture
Identify the Energy Conversions in the illustrations below.
1
6
Example:
Electrical
Sound and Light
7
2
8
3
4
9
10
5
4
What I Have Learned
Activity 4.1.3. Imagine and Draw
This activity is essential in helping you retain the knowledge you acquire by imagining
it and illustrating it. This will also help you improve your skills in drawing.
With all the sources of energy that was mentioned above, choose one source of energy
and illustrate how you imagined it before and after you have learned it in this lesson. Draw it in
a short bond paper. Be creative!
What I Can Do
Activity 4.1.5 Choosing Energy
Choose one source of renewable energy and one source of non-renewable energy and
compare their advantages and disadvantages.
Lesson
2
Active Ingredients of Cleaning Products
What’s In
Previously, we have learned how the energy we used in our community is being
harnessed and the most common sources of energy. Now, as we’re already talking about
utilities such as electricity, in our household it is not enough that our appliances can function or
our house is well-lighted. The house must be clean also! Do you know how can cleaning be
done easily and quickly? If you’re thinking of cleaning products such as soap and detergents,
then you’re right!
5
What I Need to Know
Discovering what makes those products efficient for cleaning. At the end of this lesson,
you are expected to
1. give common examples of cleaning materials for the house and for personal care
from product labels, identify the active ingredient(s) of cleaning products used at
home
2. identify the active ingredient(s) of cleaning products at home
3. give the use of the other ingredients in cleaning agents
What’s New
Activity 4.2.1. Word Twist
Rearrange the word to get the correct word. Clue: These words are related to cleaning!
1.
2.
3.
4.
VESARABSI
DIAC CIHOPHSPOR
SDECNATINIFTS
GEARDSEGES
5. GERTETDEN
What Is It
Cleaning is one of the very common household chores on our daily lives. We do
cleaning in our houses, offices and schools. Cleaning can be done easier and quicker if
cleaning products are to be used. These cleaning products come in different forms such as
liquid, powder, sprays or granules and are formulated to be used in the removal of dirt, dust,
stain, and bad smells on various areas.
The following are examples of cleaning agents:
A. Water
Water is the simplest and most common example of cleaning agent. It is extremely
easy to use, a good solvent and has stability. Water is readily available and is also
inexpensive.
B. Detergents
Detergents are agents which helps for the betterment of cleaning. It supplies the things
that water alone can’t do. One of its function is reducing surface tension of water,
emulsifying (break-up) soil and lifting it from surface, suspending soil in the cleaning
solution. It is comparatively more operative in hard water and mostly harmless.
6
C. Abrasives
Abrasives are very punitive cleaning agents. It is very hard and rough to use
since they are made up of mineral particles. Some of the commonly used abrasives are
pumice, sand, steel wool and calcite. Also, abrasives may contain alkalis (for removal of
grease), chlorine (for disinfection) and organic solvents (for dissolving grease). Abrasives
may be categorized as creams, liquids, pastes and powder, based on their texture.
D. Degreasers
Degreasers dissolve proteins using strong alkalis. They are very corrosive that usually
damage the surface. Most of the time degreasers are composed of sodium metasilicate or
caustic soda. Sodium hydroxide and sodium metasilicate are examples of strong alkalis
which play a primary role in removing solid grease. Sodium carbonate not only provide a
moderately high pH but also provides buffering to maintain pH levels upon product dilution.
Alkalis ensure that pH is maintained at a suitably high-level during cleaning. Sodium
bicarbonate (baking soda) offers alkalinity at a slightly lower pH making it useful for
buffering formulations and other uses that requires mild pH. Silicates perform additional
useful functions. They offer corrosion protection, mainly on "white" metals like aluminum.
Their other functions are for suspension of fine particles and reduction of the redeposition
of soil that has been removed from surfaces. Ammonia is commonly used as an alkali in
floor wax removers.
E. Acids
Acid is a compound that contains Hydrogen that can be replaced by a metal. It
usually has a sour taste, capable of neutralizing alkalis and it would turn a blue litmus
paper into red when tested. Phosphoric acid, a strong acid, is used for dissolving
calcium and metal salts. It is also useful in tub, tile, sink and toilet bowl cleaners
while Hydrochloric acid is a strong acid used in some toilet bowl cleaners.
F. Organic Solvents
Solvents are specifically used to remove grease and clean without leaving a residue,
particularly, window cleaners and removal of finger marks on walls. The main ingredient
of these solvents is water making it remove grease easily and is compatible with water.
G. Disinfectants
Disinfectants or antimicrobial agents are used to destroy bacteria and viruses by
interfering with their metabolism or destroying their cell walls. Various chemicals make it
possible to disinfect by alternating its structures, including alcohol, sodium hypochlorite,
iodine, pine oil, phenolics and quaternary ammonium compounds.
Active Ingredients Found in Cleaning Chemicals
A. Ammonia is a naturally occurring, colorless and soluble alkali gas. It is commonly
referred as “household ammonia” in cleaning compounds. It is regularly found
in window and glass cleaners, but mostly produced to be a fertilizer. It is an
irritant to the skin and eyes, and it may be dangerous when consumed.
B. Bleach or sodium hypochlorite is another alkali disinfectant. Bleach oxidizes or breaks
down the molecular bonds of stains and germs. Bleach
is commonly packages in the bottle as a 5 percent
solution. When bleach is mixed with acids it forms toxic
chlorine gas such as bowl cleaners.
C. D-Limonene extracted from citrus rind is a neutral compound. The straight d-limonene
are used as a solvent while d-limonene combined with a surfactant can be
7
used as a rinse able cleaning solution. Surfactants are compounds that
lowers the surface tension of water, making the molecules less likely to
stick with each other and interact more with oil and grease.
D. Enzymes and bacteria are used commonly for removal of degreasers and stains and
cleaning of drains. These live organisms consume organic
materials, for the purpose of blockage, stain or odor removal.
E. Hydrogen peroxide being an acidic disinfectant, is commonly used in a 3 percent solution
as a skin antiseptic. It also works as an oxidizer. It can also be used for
whitening of paper pulp and treating drinking water. Most of the time it
is combined with other disinfectants for greater efficacy.
F. Phenol is a manufactured substance used in disinfectants and resins; it has many forms
and goes in many names. For example, Nonyl phenol ethoxylate is regularly found
in detergents. Skin exposure to large amounts of phenol can cause damage in liver,
diarrhea, dark urine and hemolytic anemia.
Hazardous Ingredients in Household Cleaning Agents
A. Carcinogens
Carcinogens cause cancer and/or promote cancer’s growth.
B. Endocrine disruptors
Endocrine disruptors mimic human hormones, confusing the body with false signals.
Exposure to endocrine disruptors can lead to several health concerns including
reproductive, developmental, growth and behavior complications. It has been linked to
reduced fertility, premature puberty, miscarriage, menstrual problems, challenged immune
systems, abnormal prostate size, ADHD, non-Hodgkin’s lymphoma and certain cancers.
C. Neurotoxins
Neurotoxins alter neurons, affecting brain activity, causing a range of problems from
headaches to loss of intellect.
Chemicals to Avoid
A. Pesticides
Pesticides are fat-soluble, making them difficult to eliminate from the body once
ingested. It often contains carcinogens and endocrine disruptors.
B. APEs
APEs are surfactants, meaning they lower the surface tension of liquids and help
cleaning solutions spread more easily over the surface to be cleaned and penetrate
solids. APEs are endocrine disruptors.
C. Formaldehyde
Formaldehyde is commonly known as preservative. It is also a germicide, bactericide
and fungicide. It can be found in household cleaners and disinfectants. Formaldehyde is a
carcinogen.
D. Organochlorine
Organochlorine results from the combination of hydrogen and carbon. DDT is one of
the most lethal type of organochlorines. OCs are present in pesticides, detergents,
degreasers and bleaches. It is a carcinogen and endocrine disruptor.
8
E. Styrene
Styrene is a naturally occurring substance derived from the styrax tree. It is
commonly used in the manufacture of numerous plastics including plastic food wrap,
insulated cups ad PVC piping. It is also found in floor waxes and polishes and metal
cleaners. Styrene is a known carcinogen as well as endocrine disruptor. It may cause
damage to the central nervous system, liver and reproductive system when exposed.
F. Phthalates
Phthalates are most commonly used in the manufactures of plastics. It can also be
found in household cleaners and detergents. These chemicals are classified as inert and
as such no product-labeling requirements exist for phthalates. They are endocrine
disruptor and suspected carcinogen. Phthalates are known to cause hormonal
abnormalities, thyroid disorders, birth defects and reproductive problems.
What’s More
Activity 4.2.2
A. Word Search
Locate the words associated with cleaning agents and active ingredients in the grid.
The words can be running in horizontal, vertical and diagonal directions.
R
W
F
E
R
P
E
R
O
X
I
D
E
G
G
V
A
N
T
S
F
G
O
A
T
S
A
G
A
W
F
A
M
I
L
Y
S
S
A
Y
B
A
T
H
A
F
H
G
M
I
L
I
A
E
R
G
K
I
R
T
P
H
E
N
O
L
A
M
A
E
S
E
D
F
E
H
A
T
S
I
N
L
S
I
A
T
N
V
E
R
K
O
J
C
A
T
I
H
J
D
S
Z
K
A
L
G
H
A
F
S
V
F
A
I
J
O
Y
M
R
E
D
T
F
A
E
Q
E
M
G
H
A
M
A
R
Y
E
A
T
S
V
C
I
P
E
A
P
E
R
C
Y
K
U
A
B
D
L
Y
E
F
A
E
C
Y
H
H
B
A
U
R
N
P
N
S
Y
A
F
R
A
C
T
L
A
A
T
W
T
H
A
A
N
T
D
K
E
O
G
J
R
I
E
C
A
R
S
Y
E
M
R
E
S
R
A
C
I
D
F
G
J
E
F
T
S
D
W
Q
1.
6.
2.
7.
3.
8.
4.
9.
5.
10.
9
B. True or False
Write the word TRUE if the statement is correct and FALSE if the statement is wrong.
If the statement is wrong, write the correct answer, beside the word FALSE.
1. Straight d-limonene can be used as a solute.
2. Carcinogens promote cancer’s growth.
3. Bacteria consumes organic matter to remove the stain or odor.
4. Neurotoxins alter neurons, causing problems such as toothache.
5. Endocrine confuses the body with false signals.
C. Crossword Puzzle
Use the definitions as a clue to the word that goes into the corresponding blank spaces.
Across
1. These chemicals are classified as inert and as such no product-labeling requirements
exist for it.
2. It is commonly known as preservative.
3. It is fat-soluble and difficult to eliminate from the body once ingested.
Down
4. Exposure to this chemical may affect the central nervous system, liver and
reproductive system.
5. A type of organochlorine
What I Have I Learned
Activity 4.2.3 Sum It Up!
This activity is essential in helping you retain the knowledge you acquired! Write it
down to remember!
10
Materials: Short bond paper cut in 1/8 size crosswise
Make a flash card of the information about active ingredients that struck you the most.
The front portion of the flash card should contain a question about active ingredients and at
the back of the card, write the answer of the question you wrote. Attached a minimum of 10
flash cards in your answer sheet when you pass it. Remember, be creative as you can be!
What I Can Do
Activity 4.2.4 Find Me
Look around your house and list all the cleaning materials available in your household
and write in the second column the active ingredients indicated on the label.
MATERIAL
Active Ingredients
1.
2.
3.
4.
5.
Lesson
3
Use of the Other Ingredients in Cleaning Agents
What’s In
Previously, we have discussed about household cleaning products. Now let’s go to the
other uses of the active ingredients of cleaning agents. Aside from the purpose of cleaning,
the other ingredients in cleaning agents can also be used in other ways. Let’s find out how.
11
What I Need to Know
This lesson tackles about the uses of the other active ingredients of cleaning agents.
Discover the other uses of those active ingredients. At the end of this lesson, you are expected
to give the use of the other ingredients in cleaning agents.
What’s New
Activity 4.3.1 Detergent Action
Prepare the materials indicated and carefully follow the procedure provided.
Objective: To find out what detergents do to water to make it an effective cleaning agent.
Materials:
½ tsp detergent (any brand)
cotton cloth (5cm x 5 cm)
2-5 mL water
medicine dropper or drinking straw
2 small containers (any type of container as long as small in size)
Procedure:
A. Mix a pinch of detergent with 2-5 mL of water in a container.
B. Place 2-5 mL of water in another container
C. Put a drop of water and detergent solution on separate spots on a piece of
a medicine dropper.
cloth using
D. Observe how fast each drop spreads out.
E. Repeat step C for 2-3 times.
Analysis:
1. What is the shape of the water droplet on the cotton cloth? Explain.
2. Which droplet spreads faster on the cotton cloth? Explain why.
What Is It
Role of Other Ingredients
Commercial cleaning products contain other substances. These substances contribute
to the effectiveness of the cleaning agent and provide special functions. Some of them are:
12
A. Antimicrobial agents
Antimicrobial agents also called disinfectants or sanitizers are chemicals that kill
microorganisms or prevent their growth. They clean the materials to prevent of diseases
brought by bacteria, viruses, and fungi; and reduce the odor-causing microorganism.
B. Bleach activators
These are substances needed for low temperature washes and achieve the full activity
of bleaching in the wash liquor.
C. Bulking agent
This substance is added to increase the volume of a product through dilution, so that
it can be applied at the correct concentration. Bulking agents are also used for food
applications such as beverages, they can add texture without making a change on the
properties of the final product.
D. Colorant
This substance contains a blue dye or pigment that provides bluing effect when added
to laundry products. It is a substance that is added or applied in order to change the color
of material or surface. Most of the time, colorants are used in industries like paints, clothes,
plastics, prints and photographs.
E. Enzymes
Enzymes can also be used in food industry to enhance flavor, help digestion and
improve the nutritional values of the food. In textile industry, enzymes are used for treating
fibers and textiles. In cosmetics, enzymes are used to improve the quality of the personal
care products. It is also used in paper refining bleaching making the paper sheet produced
stronger, thicker and softer. Hence, enzymes are biocatalyst that can be used in many
applications, making the processes cheaper and more environmental-friendly.
F. Flavors and Sweeteners
Substances that make commercial cleaning products appealing to the consumers.
These substances provide sweet taste but has no calories of carbohydrates. It is commonly
used as sugar-substitute. Most toothpaste have flavors and sweet tastes.
G. Fragrances
These are substances used to mask the odor of ingredients and packaging of the
cleaning agent. They provide pleasant odor to fabrics and skin and gives special identify to
a product.
H. Optical Brighteners
These are fluorescent dyes. They absorb ultraviolet rays in sunlight and transmit them
as blue light. This blue light masks the yellowish color of the clothes and increases the
amount of visible light reaching the eye, giving the white garment a whiter appearance.
I. Preservatives
Substances that prevent product spoilage during storage. They are required in laundry
liquids. The surfactants and enzymes in detergents and other cleaning agents are
biodegradable and can be attacked by bacteria, which causes the product spoilage.
13
What’s More
Activity 4.3.2
A. Fill Me In
Read the question and fill in letters to complete the word and get the correct answer!
1. I provide color to different products. Making the things you like colorful!
_ _ L _ _ A _ T
2. I prevent spoilage on the products. Keeping it fresh as it could be!
_ R _ _ E _ _ A T _ V _ _
3. I am used to add volume for the products without changing the quality of it!
_ U _ K _ _ G
_ G_ N_
4. I protect you from bacteria and virus that can cause sickness. I am a bacteria killer!
A _ _ I _ I _ R _ _ I A _
_ G_ N_ S
5. Can you smell it? That’s me! I make the soap you like smells good!
_ R _ _ R _ N _ _ E S
4.3.2 B. Essay.
Read the article from
Schoolgirl Suffers Severe Allergic Reaction to L’Oreal Hair Dye
by Dawn, April 16, 2009
Today the Daily Mail reported a story about Carla Harris, a 15-year-old schoolgirl who
suffered a potent allergic reaction to L‟Oreal Recital hair dye, causing her head to swell up to
twice its normal size, leaving the teenager in agony for several days. Despite conducting a
patch test prior to using the product, Carla still had a severe reaction after using the L‟Oreal
hair dye and was admitted into hospital and treated with antihistamines and steroids. Carla
and her mother Lynn have called for the banning of paraphenylenediamine (PPD), the toxic
chemical that doctors suggested caused the problem. Two-thirds of hair dyes contain PPD,
which was banned from use in hair dyes in the 20th century in Germany, France and Sweden,
because concerns arose about its harmful effects. I can sympathize, when I was 16 years old
after several years using hair dyes without adverse reactions, I applied a semi-permanent hair
dye which caused over a third of my hair to fall out. Unfortunately, it never grew back and in
subsequent years more of hair fell out. I just put it down to me being sensitive, but my mother
told a woman at her workplace about my unfortunate incident with the hair dye and she
explained that her daughter had used the very same hair dye and all of her hair had fallen out.
It wasn’t until many years later that I began to research the toxicity of ingredients used in
cosmetics and other beauty products.
14
Guide Questions:
1. What happened to Carla Harris?
2. What happened to the author of the text when she was 16 years old?
3. Do you think that this article aims just to inform? Or is it to persuade?
4. What is the message of the article?
5. If something similar happened to you, would you be that concerned on the topic?
What I Have Learned
Activity 4.3.3. Remember Me
This activity is essential in helping you retain the knowledge you acquired. Write it
down to remember.
Make a flash card of the key terms about active ingredients. Attached a minimum of
10 flash cards in your answer sheet when you pass it. Remember, be creative as you can be.
Materials: Short bond paper cut in 1/8 size crosswise.
Procedure: The front portion of the flash card should contain the Key Term and
the back of the card, write the definition of the key term you wrote.
at
What I Can Do
Activity 4.3.4. Inventory Making
Think about all the products you use every morning when you wake up. How many of
them do you think involve chemistry? Identify from the product labels the active ingredients of
these cleaning agents and write the uses of the listed active ingredients.
PRODUCT
ACTIVE INGREDIENTS
1.
2.
3.
4.
5.
15
USES
Summary
Sources of Energy
● Energy is the ability to do work. It cannot be destroyed nor created, energy can
only be transferred or changed from one form to another.
● Energy can be renewable and non-renewable.
● Examples of renewable energy are solar energy, wind energy, hydropower,
geothermal and biomass. While examples of non-renewable energy are the
following; fossil fuel oil, nuclear, natural gas, and coal.
Active Ingredients of Cleaning and Personal Care Products
 The most common cleaning agents are water, detergents, abrasives,
degreasers, acids, organic solvents and disinfectants.
 Cleaning chemicals active ingredients are usually ammonia, bleach, Dlimonene, Enzymes, hydrogen peroxide and phenol.
 Some household cleaning agents contains carcinogen, endocrine disruptor and
neurotoxin that are harmful to the human body.
 Always look out for pesticides, APEs, organochlorines, styrene and phthalates.
Avoid exposure as much as possible.
 The active ingredients present in the cleaning agents can also be used in
different products such as in food industry, textile, beverages etc.
16
Assessment: (Post-Test)
Multiple Choice: Write the letter of the best answer.
1. Which of the following is a nonrenewable energy resource?
A. Coal
B. Hydroelectric
C. Methane
D. Solar
2. What energy resources are derived from natural organic materials?
A. Biomass
B. Fossil Fuels
C. Geothermal sources
D. All of these
3. What type of renewable energy comes from tapping heat generated inside the
Earth?
A. Biomass
B. Geothermal energy
C. Hydrothermal energy
D. Solar energy
4. What type of renewable energy comes from capturing the power of the sun's rays?
A. Geothermal energy
B. Hydrothermal energy
C. Solar energy
D. wind energy
5. Why does the world face an energy crisis?
A. World demand for energy will increase
B. World oil production will peak and begin to decline
C. Shortages and the resulting escalation of prices can shock the economic and
political order
D. All of the above
6. Why do we discuss about energy crisis when energy can neither be created nor
destroyed?
A. Energy transform into different form continuously.
B. Usable form of energy is dissipated to the surroundings in less usable forms.
C. Energy is consumed and cannot be used again.
D. All of these
7. Which is the ultimate source of energy?
A. Fossil fuels
B. Sun
B. Uranium
D. Water
8. What is a detergent?
A. A cleaning agent that is soluble in water and combines with dirt to make it soluble
in water too.
B. Any cleaning agent that is soluble in water
C. Any cleaning agent that is insoluble in water
D. A cleaning agent that is insoluble in water and combines with dirt to make it
insoluble in water too
9. Which of the following household chemicals is the main ingredient in bleach or
bleach products?
A. Ammonia
B. Sodium bicarbonate
C. Sodium hypochlorite
D. Sodium lauryl sulfate
17
10. Which of the following is NOT a chemical?
A. Ammonia
B. Ammonium lauryl sulfate
C. Hydrogen gas
D. Water
11. Which of the following is NOT a carcinogen?
A. APEs
B. Formaldehyde
C. Pesticide
D. Styrene
12. What active ingredient kills microorganism?
A. Anti-microbial Agent
B. Bulking Agent
C. Enzymes
D. Preservatives
13. Which among the choices is true about the bulking agent?
A. It gives color to the product.
B. It enhances the flavor of the product.
C. It adds volume to the product without altering the quality.
D. It prevents bacteria and viruses in sticking to your clothes.
14. How does the optical brighter make white garment a whiter appearance?
A. By enhancing the odor of the garment.
B. By reflecting white lights from the sun.
C. By absorbing ultraviolet rays in sunlight and transmit them as blue light.
D. None of the above, it’s bleach that makes the garment whiter.
15. What substance promote full activity of bleaching process?
A. Bleach Activator
B. Bulking agent
C. Detergent
D. Water
18
nioighigSh S
hohool ol
Physical Science
Quarter 2 - Module 1
How We Come to Realize that the Earth
is Not the Center of the Universe
19
Table of Contents
What This Module is About
………………………………………………………………………………………..
…….
i
What I Need to Know ...............................................................................................................................................
ii
How to Learn from this
ii
Module………………………………………………………………………………………..
iii
...
Icons of this Module
…………………………………………………………………………………..……
…………………
1
1
What I Need to
Know…………………………………………………………………………………… 1
…………………...
Lesson 1:
How the Greeks Knew that the Earth is
Spherical………..………….……
2
3
4
4
What I Need to Know:
………………………………………………….………………………….…
….…….
What’s New: And the Shape Is
………………………………………………..………………..….……..
What Is It: Sphere It Is
……………………………………………………………………………….....….
….
What’s More: What is the Evidence Again?........................................................................
What I Have Learned: Synthesizing your
Learning……………………………………….……
What I Can Do: DepEd TV Live
……………………………………….………………………………...
Lesson 2:
Astronomical Phenomena Known to Astronomers
Before the Advent of Telescopes
…………………………….………….………..…………
What’s
In
……………………………………………………………….…………
………………….…….
What I Need to
Know………………………………………………………………………
….……..
What’s New: What’s the Word
……………………………….……………………….…..……
What Is It: Pre- Telescope Observed Phenomena
………………….………………
What’s More: The Phases of the Moon and
Me……………………………………….
What I Have Learned: Synthesizing your Learning
……………………………….…
Lesson 3:
20
6
6
6
6
7
8
9
What I Can Do:
Brahe’s
The Sun’s Movement ................................................................................. 9.
Innovations ................................................................................ 10
What’s In ...................................................................................................................... 10
What I Need to Know ..................................................................................... 10
What’s New: The Who ................................................................................... 10
What Is It: Tycho Brahe’s Contribution ................................................................... 11
What’s More: The Data Says .......................................................................... 13
What I Have Learned: Here’s My Take................................................................... 13
What I Can Do: As I Ponder On..................................................................... 13
Summary............................................................................................................................... 14
Assessment: (Post-Test) ....................................................................................................... 15
Key to Answers ..................................................................................................................... 17
References............................................................................................................................ 19
21
What This Module is About
Physics is everywhere it comprises all the laws that govern minute objects to a
matter of cosmic proportion. That is why it is considered basic science.
This module covers the first three ideas of the second part of this two-part Physical
Science core subject which is Physics. This particularly dwells on the views and ideas of the
ancient philosophers on the spherical shape of the Earth. This also covers the discoveries of
other planets and cosmic happenings even before the invention of the telescope including the
utilization of the vast data collected by Brahe in the formulation of laws of planetary motion by
Kepler.
Together, let us scan the next few pages of this module for us to appreciate the work
of the ancient great thinkers. Through their wit and keen observation, the foundational ideas
on how this universe worked have been laid out, built upon and refined as time goes by.
This module contains varied activities that can help you as a Senior High School
student to not just gain knowledge on how they came about ideas of the Earth and the cosmos
but most importantly learn from them on how they utilize this knowledge and information in
making their lives better.
This module covers the following lessons:
1. How the Greeks knew that the earth is spherical
2. Astronomical phenomena known to astronomers before the advent of telescopes
3. Brahe’s innovations
What I Need to Know
At the end of this module, you should be able to:
1. Explain how the Greeks knew that the Earth is spherical (S11/12PS-IVa-38)
2. Cite examples of astronomical phenomena known to astronomers before the advent of
telescopes (S11/12PS-IVa-41)
3. Explain how Brahe's innovations and an extensive collection of data in
observationalastronomy paved the way for Kepler’s discovery of his laws of
planetary motion (S11/12PS-IVb-44)
i
How to Learn from this Module
To achieve the objectives cited above, you are to do the following:
•
Take your time to read the lessons carefully.
•
Follow the directions and/or instructions in the activities and exercises diligently.
•
Answer all the given tests and exercises.
Icons of this Module
What I Need to
Know
This part contains learning objectives that
are set for you to learn as you go along the
module.
What I know
This is an assessment as to your level of
knowledge of the subject matter at hand,
meant specifically to gauge prior related
knowledge
What’s In
This part connects the previous lesson with
that of the current one.
What’s New
An introduction to the new lesson through
various activities, before it will be presented
to you
What is It
These are discussions of the activities as a
way to deepen your discovery and
understanding of the concept.
What’s More
These are follow-up activities that are
intended for you to practice further to master
the competencies.
What I Have
Learned
Activities designed to process what you have
learned from the lesson
What I can do
These are tasks that are designed to
showcase your skills and knowledge gained
and applied to real-life concerns and
situations.
ii
What I Know
Multiple Choice. Select the letter of the best answer from among the given choices.
1. Which of the shapes below represents the belief of the Greeks about the shape of the
Earth?
A
B
C
D
2. Which among the philosophers measured the Earth’s circumference?
A. Aristotle
B. Pythagoras
C. Plato
D. Eratosthenes
3. How did the Greeks especially Aristotle use the lunar eclipse phenomenon to explain that
the Earth is not flat?
A. He noticed that the shadow casts by Earth on the moon is round.
B. He argued that since the shape of the moon appears to be round then the Earth
must also be round.
C. He argued that lunar eclipse only happens when a round opaque object blocks the
passage of sunlight.
D. He noticed that all things seemed to be moving around the Earth except for Earth
itself.
4. Which of the following is true about how the Greeks knew that the Earth is not flat?
A. They observed that Earth is rotating on its axis.
B. They noticed that even in short travels northwards the Pole star is higher in the
sky.
C. They have seen Earth from outer space.
D. They observed that during a solar eclipse, Earth is temporarily covered with
darkness during the daytime.
5. Which time of the year did Eratosthenes observe the pillar in Alexandria cast a shadow?
A. noontime during spring
B. noontime during the summer solstice
C. noontime during solar eclipse
D. noontime during the winter solstice
6. Which of the following astronomical phenomena was already observed by the ancient
people even before the telescope was invented?
A. sunspot
B. solar eclipse
C. craters of the moon
D. atmosphere of Mars
7. Which of the following objects would most likely cast a shadow on the moon during a lunar
eclipse when it is observed here on Earth without the aid of a telescope?
A. Sun
B. Moon
C. North star
D. Earth
8. Which phase of the moon is shown in the figure below?
A. full moon
C. new moon
B. first quarter moon
D. last quarter moon
Iii
9. Which phase of the moon is shown in the figure below?
A. full moon
B. first quarter moon
C. last quarter moon
D. new moon
10. How did the ancient astronomers discover that Mercury and Venus are planets not stars?
A. They noticed that the stars are in a fixed position to each other. But they have
observed that there are very bright stars wherein its positions periodically change.
B. They noticed that Mercury and Venus are bigger compared to the other stars.
C. They noticed that the constellations’ positions in the night sky vary depending on
the time of the year.
D. They noticed that the stars change positions periodically. But there are very bright
stars in a fixed position to each other.
11. Which of the concept below is Tycho Brahe’s major contribution to the field of astronomy?
A. the Earth’s pull of gravity on the moon
B. measurement of Earth’ circumference
C. accurate measurement of stars’ and planets’ position
D. the invention of the telescope
12. Kepler’s first law of planetary motion is known as
.
A. Law of Ellipses
B. Law of Gravity
C. Law of Periods
D. Law of Equal Areas
13. Which of the following statements bests describe Brahe’s model?
A. The planets except Earth revolve around the Sun, while the moon and the Sun
revolve around the Earth.
B. The Sun and the Earth are both at the center and the other planets revolve around
it.
C. All the planets revolve around the Sun while the moon revolves around the Earth
D. Neither the Sun nor the Earth is at the center and the other planets do not revolve
around it.
14. Kepler discovered that planets do not go around the Sun at a uniform speed but it
depends on its position relative to the Sun. What is its speed when it is closer to the
Sun?
A. faster
B. neither fast nor slow
C. slower
D. similar to the speed when it is
farfrom the sun
15. What relationship did Kepler discover between the times of revolutions of the planets and
their distance from the Sun?
A. The square of the times of revolution of the planets are proportional to the cube of
their average distance from the Sun.
B. The square of the times of revolution of the planets is not proportional to the cube
of their average distance from the Sun.
C. The cube of the times of revolution of the planets are proportional to the square of
their average distance from the Sun.
D. The cube of the times of revolution of the planets is not proportional to the square
of their average distance from the Sun.
iv
How the Greeks Knew that the
Earth is Spherical
What I Need to Know
You have probably gazed at the sky on a clear night and wonder about whether there
are aliens or parallel universes out there. With the advent of space explorations, the notion of
living on Mars has already been entertained by some people just in case Earth ceased to be
a habitable planet in the future. Or maybe you imagined taking a vacation on board on a space
ship and your destination is outer space! Isn't it cool?
Ancient people perhaps did not think about aliens or the parallel universe or thought
of going to Mars, but one thing is sure they too were curious about their surroundings and tried
to seek answers and explanations.
In this lesson, you will be able to explain how the Greeks knew that the Earth is
spherical.
What’s New
Activity 1.1.1 And the Shape Is
Aim: To find out the shape of the shadow
Materials: - Actual Flashlight or use the flashlight app of the mobile phone (if both materials
are not readily available, you may use a lighted candle .Caution: Be sure to put
off the candle immediately after use)
- Two spherical objects; 1-big, 1-small (alternative: make your own balls using
crumpled used papers;1-big, 1-small)
- ruler
Procedure:
1. Align the flashlight
and the balls
horizontally.
2. Point the flashlight to
one of the balls.
3. Observe the shadow
it casts on the ball
behind it.
(Note: Perform the
activity in a darkened
room or during night time)
Fig.1.1.1. The flashlight and the two balls are ligned
with each other.
Questions:
1. What is the shape of the shadow cast by Ball 1?
2. Which of the two balls represents the Earth? the Moon?
3. Supposed that the moon or Earth is a heart shape, what shadow would it form
whensunlight is aligned with it? Why?
1
What Is It
Sphere It Is
Did your careful observation prove you right? Just like you, before the Greeks and the
rest of the ancient people were able to formulate theories of the sky and the Earth, they made
a careful and repetitive observation of the phenomena around them.
The Mesopotamians as accounted in their mythology around 6th century BC described
Earth as a flat disk floating in the ocean and bounded by a spherical sky. This idea has
prevailed for hundreds of years until a new view was presented.
As the quest for knowledge continues and civilization prospers, several models of the
universe were presented. And it is categorized as a geocentric model or Earth-centered and
heliocentric model or Sun-centered. In the geocentric model, the Earth was at the center
and the rest of the planets and heavenly bodies revolved around it. While in the heliocentric
model, the Sun was at the center and the rest of the heavenly bodies including the Earth
moved around it.
In all of the geocentric models of the universe, the Earth and other heavenly bodies
were assumed to be spheres. They were convinced that the shape of the Earth was not flat
instead it was spherical. This idea was already entertained by Pythagoras and Plato however
they do not have concrete evidence to support their claim. Until Aristotle (around 320 BC), a
student of Plato presented his arguments that established the claim during their time.
Aristotle argued that:
- the sphere is perfectly solid and the heavens are a region of perfection
- the Earth's component pieces, falling naturally towards the center, would press
into a round form
- in an eclipse of the Moon, the Earth's shadow is always circular thus, if Earth is
aflat disc, it would cast an oval shadow
- even in short travels northwards the Pole Star is higher in the sky.
Another phenomenon considered by Greeks in their claim of Earth's spherical shape
was navigation. They observed that when ships sails away, it seems that it gradually
disappears behind the horizon.
Is there still other evidence that you know about that are not listed here? Can you
name them?
If it is not a sphere then why measure its circumference
One of the astronomical events that fascinated the early civilization was the eclipse.
And the recorded information about eclipses was used by Eratosthenes (about 235 BC) to
approximate the circumference of the Earth. This was another proof presented about the
spherical shape of the Earth. As you know an eclipse is a shadow formation. This happens
when the path of light rays is blocked by an object.
While working as a librarian at the University of Alexandria in Egypt, he came across
information that during summer solstice especially at noontime, sunlight shines directly down
a deep well in Seyene, a city south of Alexandria and reflected up again and no shadow is
cast by any object on a noontime.
But in Alexandria at the same date and time, a vertical pillar and other structures cast
a shadow.
2
And so, Eratosthenes measured the shadow cast by a vertical pillar in Alexandria and
he found out that it is 1/8 of the height of the pillar.
This is roughly equivalent to
a 7.2 angle between the sun's rays
and the vertical pillar while in Syene
it's 00. Based on his calculation,
7.20 is equivalent to 1/50 of a circle.
Thus, it follows that the distance
between Alexandria and Syene
must be 1/50 the circumference of
the
Earth.
Or
the Earth's
circumference is 50 times the
distance between the two cities.
Since these two cities are frequently
traveled,
the
distance
was
measured to be 5000 stadia (800
kilometers).
So
the
Earth's
circumference is 50 x 5000 stadia =
250 000 stadia.
0
Fig 1.1.2. When the rays shine directly above at Syene, it is
directly overhead at Alexandria which around 800
north. The pillar in Alexandria cast a shadow, while
water in the deep well at Syene directly reflected
sunlight.
not
km
the
the
Are you now convinced that indeed the Earth is spherical?
What’s More
Activity 1.1.2: What are the Pieces of Evidence Again?
Aim: To share the information about the pieces of evidence of Earth's spherical shape through a
graphic organizer.
Materials: 1- long size bond paper/ cartolina of any color cut into long size bond paper
a pair of scissors
coloring materials
ruler
Instructions:
Make a trifold foldable using the long size bond paper. Just follow the word and
graphic instructions below.
a. Fold lengthwise the long size bond paper (8.5 x 13 inches bond paper/cartolina.) Using a
ruler, measure around 4.3 inches from the long side of the bond paper and fold the paper
from the 4.3 inches mark then fold again so that you can create the tri-fold foldably. Cut
down the two folds to the centerfold. In each flap, write down the evidence of the spherical
shape of the Earth. Organize the pieces of evidence by the philosopher. To make the
organizer more creative, illustrate your interpretation of the pieces of evidence.
4.3 in
b. Fold the three flaps down. In the flap write the name of the astronomer where the evidence
is credited to. If the evidence is not credited to a philosopher, simply write other evidence/s.
3
Then fold the two side flaps toward the center panel. Write the concept title onto the front
flap. An appropriate design on the title flap may also be added.
4
Front
flap
c. Paste your tri-fold foldable in your answer sheet.
What I Have Learned
Activity 1.1.3: Synthesizing Your Learning
Answer the following questions based on your learning. Be brief and concise.
Of all the arguments presented by the Greeks as proof that the Earth is spherical, which
among you find more convincing? Why?
What I Can Do
Activity 1.1.4: DepEd TV Live
You are a scriptwriter and at the same time actor of a production outfit for an
educational television show. You will feature in your show's next episode the evidence
presented by the Greeks about the spherical shape of the Earth. Choose only 2 pieces of
evidence and prepare a script for it. Make a video presentation based on the script. Your
segment will run for two (2) minutes. To make your presentation more convincing, it should
include correct information and must be interesting and creative. The language format of your
show is in Filipino/English.
Note: Videographer and extra casts or actors may be recruited for this activity but it should
be limited to the members of your family.
DepEd TV Live Activity Rubric
Criteria
Accuracy
10 points
The data included in
the presentation are
well researched.
8- 6 points
The data included in
the presentation
contain a few minor
errors.
5-4 points
The data included in
the presentation
contain a few errors.
Visual Appeal
The presentation
shows visually
appealing images
and artistic.
The presentation
has a few images
that are not visually
appealing and fairly
artistic.
The presentation's
images are not
visually appealing
and not artistic.
SCORE
Total Score
4
Creativity
The presentation is
very creative and
interesting
The presentation is
fairly creative and
interesting
The presentation
lacks creativity and
is not interesting
Lesson
2
Astronomical Phenomena
Known to Astronomers Before
the Advent of Telescopes
What’s In
In lesson 1, we have learned about how the Greeks knew that the Earth is spherical.
The presented evidence like the arc shape of the shadow cast by Earth on the moon during a
lunar eclipse and mathematical evidence given by Eratosthenes when he measured the
circumference of the Earth.
What I Need to Know
In this lesson, we will learn more about the examples of astronomical phenomena
discovered by astronomers even before the invention of the telescope.
What’s New
Activity 1.2.1: What’s the Word
Aim: To identify the words from the puzzle that has something to do with astronomical
phenomena.
Instructions:
Encircle 10 words about the phenomena or things discovered by ancient astronomers
before the advent of the telescope. The words can be read horizontally, vertically or diagonally.
Search for the following words:
 lunar eclipse
 solar eclipse
 full moon
 new moon
 first quarter moon
 shadow
 stars
 sunset
 Mercury
 Venus
What Is It
Pre- Telescope Observed Phenomena
In this modern time, we come to know of the things around us because there are
appropriate instruments or gadgets used to study or analyze such an event or phenomenon.
6
Taking for example the telescope, it is one of the instruments invented by mankind that is very
useful in studying the cosmos. But despite the absence of the telescope in ancient times, still
they were able to discover some astronomical phenomena. Just like the periodic motion of the
sun across the sky, they noticed that the sun rises from the east and sets in the west. Below
is the list of other pre-telescope astronomical events studied by ancient people.
1. Phases of the Moon
The appearance and
path of the moon were
observed
by
ancient
people to change within
29.5 days. They observe
that the moon changes
appearance from a thin
semi-circular disk to a full
circular disk. The periodic
change of the moon's
phases was the basis of the
ancient calendar.
Fig.1.2.1 Moon's relative position to the Sun as it moves around the
Earth attributes its changing appearance as viewed from the
Earth
2. Lunar Eclipse
One of the things that
caught the attention of the ancient people was the time in a month when the moon or part
of it seemed to be covered by a shadow for a brief moment. A phenomenon such as this is
known as a lunar eclipse. A lunar eclipse occurs when Earth is between the moon and the
Sun, Earth casts a shadow on the moon.
Fig. 1.2.2
A lunar eclipse occurs
Earth’s shadow is cast on
the moon.
3. Solar Eclipse
A solar eclipse happens when the moon is in between the Sun and the Earth and the
moon partially or completely blocks out the Sun. This caused temporary darkness on a day
time, thus, ancient people feared the occurrence of a solar eclipse since they associate it with
the wrath of God.
Fig. 1.2.3
A solar eclipse occurs
when a moon’s shadow
is cast on Earth
7
4. The Motion of the Stars
The astronomers noticed that the constellations’ positions in the night sky vary
depending on the time of the year. It was also observed that the stars seem to be attached
to a celestial sphere that rotates around an axis in one day.
5. Visibility of Planets
They noticed a few stars in heaven are relatively brighter than the rest of the stars. The
distant stars seemed to be fixed in their position but these stars change positions
periodically, thus the Greeks called it "wanderers" or planets. These wandering stars are
named Mercury, Venus, Mars, Jupiter, and Saturn which later discovered to be planets, not
stars.
Now that you have learned about the different astronomical events even before an
instrument like a telescope was invented. From the information that they gathered, it has
resulted in innovation and invention. One of these is the calendar.
With the use of a calendar at home, how about you try tracking the change of phase of the
moon without necessarily looking at the sky at night time. In most of the modern calendars,
the moon's movement is indicated.
What’s More
Activity 1.2.2: The Phases of the Moon and Me
Aim: To keep track of the periodic change of the phase of the moon for three months.
Materials: Calendar of the current year that indicates the movement of the moon
Procedure:
1. Choose three consecutive months of the current year (ex. January – March or
Februaryto April).
2. For every month, check out the dates of the four major phases of the moon (1st
quarter,full moon, last quarter and new moon).
3. Using the table below, list down the dates.
Month/ Phases
A
B
C
Ex. July 2020
Last
Quarter
13
Full Moon
5
New
Moon
21
4. Then count the number of days’ interval from one phase to another.
A
B
Days interval/Month
Ex. July 2020
Full moon – Last quarter
Last quarter – New moon
New moon- First Quarter
First Quarter of the current month and
the full moon of the next month
8
8
7
July-Aug
6
29
Total no. of days to complete the cycle
8
First
Quarter
28
C
Questions:
1. How many days would take the moon to complete the cycle for:
Month A
Month B
Month C
2. What have you noticed with the time interval as the phase changes from one phase to
another within three months? What is the average time to complete the cycle?
What I Have Learned
Activity 1.2.3: Synthesizing Your Learning
Answer the following questions based on your learning. Be brief and concise.
1. How is a solar eclipse different from a lunar eclipse?
2. How did the ancient astronomers identify the visible planets from the rest of the stars?
What I Can Do
Activity 1.2.4: The Sun’s Movement
Aim: To keep track of the movement of the Sun particularly during sunrise and sunset.
Instructions:
1. Listen to the announcement over the radio or watch TV for the weather bulletin a
day before you make your observation on the expected time that the sun will rise
in the morning and sets in the afternoon the following day.
2. Be sure to rise early on the next day.
3. Choose a location that you can have a good vantage point for both the sunrise
and sunset.
4. Observe the movement of the Sun during sunrise for 1 hour. For the sunset
watching, do it 40 minutes before the expected time that the sun will set.
5. Draw or illustrate the pattern of the sun's movement within 1 hour in the morning
and 40 minutes before sunset.
6. Use any size of bond paper for your illustration.
7. Give a short description of the observation you have made.
8. Paste the output in your science activity notebook.
Sample layout
9
Name:
Grade and section:
Date:
Subject:
THE SUN’S MOVEMENT
During sunrise
During sunset
Drawing
Drawing
Brief description
Brief description
1
0
Lesson
3
Brahe’s Innovation
What’s In
In lesson 2, we have learned about the discovery of astronomical wonders even
without the aid of an instrument especially the telescope. Aside from that they also made us
realize that our surroundings not only heavens have a great influence on one's way of living.
What I Need to Know
In this lesson, you will be able to explain how Brahe's innovations and an extensive
collection of data in observational astronomy paved the way for Kepler's discovery of the laws
of planetary motion.
The knowledge about the universe starting from the ancient time up to the present has
proven to be a dynamic one. The discoveries weakened the foundation of a theory that thought
to be correct and widely accepted for quite a long time. And in the process of revolutionizing
the idea, one must be able to back the claim with proof. The best proof one could present is
data that is verified and tested several times. Just like the works of Tycho Brahe.
But before we discuss further the concept, let’s try to look back and look ahead of the
who’s who in the field of astronomy by associating the names of astronomers, mathematicians
or scientists and their contributions by answering the activity on the next page. If you are not
certain of your choice, don’t worry just give it a try.
What’s New
Activity 1.3.1: The Who
Match the names in column A with their corresponding contribution in column B. Write the
letter that corresponds to your answers on the space provided.
Column B
Column A
a. proponent of the universal law of gravitation.
1. Eudoxus
2. Tycho Brahe
3. Aristotle
4. Claudius Ptolemy
5. Johannes Kepler
6. Galileo Galilie
7. Eratosthenes
8. Aristarchus of Samos
9. Nicolaus Copernicus
10. Isaac Newton
b. invented his own telescope and discovered the craters of the
moon and gathered proof that supports the claim of
Copernicus
c. proposed the geo-heliocentric universe model
d. proposed the first idea of a heliocentric universe.
e. proponent of the laws of planetary motion
f. calculated the Earth’s circumference
h. proposed a geocentric model of the universe where Earth is
atthe center and is layered with earth, water, air and fire.
i. proponent of a heliocentric universe wherein a
movingEarth is revolving around the Sun
j. proponent of the Earth-centered model universe where Earth
lies stationary at the center of the celestial sphere.
k. proposed a homocentric and concentric universe
11
What Is It
Tycho Brahe’s Contribution
If you got all the answers in Activity 1.3.1 correctly and correlate it with the timeline in
Fig.1.3.1., you will see that the geocentric universe model has prevailed for thousands of
years.
Fig. 1.3.1
The timeline
of some of
the who’s
who in the
field of
astronomy
and
mathematics
Only in the latter part of the 16th century that this idea was questioned by Copernicus
wherein he proposed that it's the Sun, not the Earth is the center of the universe.
The conflicting ideas and
pieces of evidence in both models
have pushed Brahe to come up with
his own model. Backed with his
accurate measurement of the
distance and positions of the planets
and stars, he proposed the
geoheliocentric model of the
universe, a hybrid of the geocentric
model of Ptolemy and the
heliocentric model of Copernicus. In
his model, the Sun orbited Earth,
while the other planets orbited the
sun.
Fig. 1.3.2 Brahe's model of the universe is also called the
Tychonic model. It is considered as a hybrid of geocentric and
heliocentric models of the universe.
It was also during this time that Brahe met the young German mathematician Johannes
Kepler. Brahe hired Kepler as a sort of "research assistant" primarily to prove that Brahe's
model the geoheliocentric model is the right model. Kepler's task is to fit in the data collected
by Brahe into the model he proposed by doing the mathematical calculation. Unfortunately,
Brahe died before his model is proven. Kepler inherited a vast set of data that will prove crucial
for developing his Three Laws of Planetary Motion later. Kepler spent many more years trying
out many possible models to fit the available data that he inherited.
But Kepler failed to reconcile the data on hand with the model Brahe proposed
especially on the notion of the stationary Earth. It took another brilliant mind and his invention
of the telescope to prove that Copernicus was right in proposing that Earth after all is not the
center of the universe.
12
But despite everything still, something good came out of his persistence, after about
20 years or so working with the data he got from Brahe; the Three Laws of Planetary Motion
were published in two different years:
First Law: Law of Elliptical Orbit or Law of Ellipses (1609)- The planets move in
elliptical orbits with the Sun at a focus (F1). The other focus (F2) is empty.
Fig. 1.3.3 Law of
Ellipses
Second Law: Law of Equal Areas (1609)-As the planets orbit around the sun, the
planets cover equal areas in equal times. For this to happen, as shown in the figure
below the point A to B when the planets are nearest to the Sun it moves and lowest
at point C to D when the planets are farthest from the Sun. When the planet is
nearest to the Sun, it is called perihelion. When it is farthest from the Sun, it is
called aphelion.
Fig 1.3.4 Law of Equal Areas
Third Law: Law of Periods (1619)-The ratio of the squares of the periods (the time
needed for one revolution about the Sun) of any of the two planets revolving around the Sun
is equal to the ratio of the cubes of their mean distances from the Sun. That is if T1 and T2
represent the periods for any two planets, and r1 and r2 represent the mean distances from the
Sun, then
If we are to rewrite
this
𝒓𝟑
= 𝒓𝟑
𝟏
𝑻𝟐𝟏
𝟐
𝑻𝟐𝟐
Meaning that r3/T2 should be the same or constant for
each planet. To determine the value of proportionality
constant k, the value of Earth’s known orbit could be
used:
TEarth = 365.24 days
r Earth = 149 million kilometres or
149 600 000 km or 149.6 x 106 km
So, r3/T2 = k or proportionality constant
𝒌𝒎𝟑
(149.6 𝑥 106 𝑘𝑚)3
= 𝟐. 𝟓𝟏𝒙𝟏𝟎𝟏𝟗
(365.24 𝑑𝑎𝑦𝑠)2
𝒅𝒂𝒚𝒔𝟐
12
Thus, the ratio of the cube of the mean distance of Earth from the Sun and the square of its
revolution is 𝟐. 𝟓𝟏𝒙𝟏𝟎𝟏𝟗
𝒌𝒎𝟑
.
𝒅𝒂𝒚𝒔𝟐
12
Based on the result of the calculation, do you think this is also true for other planets and
heavenly bodies?
What’s More
Activity 1.3.2: The Data Says
Now that you know that the data left by Brahe to Kepler proved to be accurate that is
why he was able to discover the three laws of planetary motion. So to verify it yourself, why
don't you complete the table below with your own result of the calculations applying the law of
periods. For easy calculation, please use a scientific calculator. Earth's data is already
supplied to you.
PLANET
Mercury
Venus
Earth
Mars
Planetary Data Applied to Kepler’s Third Law
r3/T2
MEAN DISTANCE
PERIOD
𝒌𝒎𝟑
FROM THE SUN
in
(T in days)
(r in kilometers)
𝒅𝒂𝒚𝒔𝟐
6
57.9 x 10
88.023
6
108.2 x 10
224.623
6
149.6 x 10
365.24
2.51 x 1019
6
227.9 x 10
686.651
Show at least one of the solutions here. Just follow the example given for Earth.
Note: For the computations, use a scientific calculator.
What I Have Learned
Activity 1.3.3: Here’s My Take
Answer the following questions based on your learning.
1. In what way that the data collected by Brahe paved the way in the discovery of the laws
of planetary motion?
2. According to the Law of periods that the ratio of r3/T2 is the same for each planet, so
what do you think is the period of revolution of an imaginary planet if its mean distance
from the Sun is 337.9 x 106 km? Comparing its period of revolution to Earth, is the
imaginary planet near or far from the Sun? Show your solution.
What I Can Do
Activity 1.3.4: As I Ponder On
As you go through the lesson, it can be noted that there are prominent ideas that many
thought to be true and correct for hundreds or even thousands of years can become out-dated
or no longer correct when pieces of evidence especially accurate data are presented. What
important life lesson can you get from this?
13
Summary

The Greeks believed that the Earth is spherical.

Aristotle argued that the Earth is spherical based on the following:
 Every object on Earth is compressed and converged toward the center forming
a sphere;
 The North Star was believed to be at a fixed position in the sky. However, when
the Greeks traveled to places nearer the equator, they noticed that the North
Star is closer to the horizon;
 During a lunar eclipse, the shape of Earth's shadow reflected on the Moon's
surface is circular.

Eratosthenes estimated the Earth's circumference by observing the shadow casts by
a pillar and correlating it with the information that while an object in Alexandria during
noontime cast a shadow, in Seyene the light rays that hit the water well is reflected
back thus, no shadow is formed. This is another proof presented to support the idea
that the Earth is indeed round.

Examples of astronomical phenomena known to man even before the invention of the
telescope are the different phases of the moon, lunar and solar eclipses, the motion of
stars, the discovery of planets Mercury, Venus, Mars, Jupiter, and Saturn.

Tycho Brahe calculated with high accuracy the positions of planets, moon and the Sun.
He proposed a geo-heliocentric model, Earth is fixed and the Sun revolves around
it. But the rest of the planets revolve around the Sun.

Johannes Kepler was hired by Brahe to assist him in looking for more data to support
his geo-heliocentric model.

The data that Brahe collected did not help in proving his idea of a stationary Earth,
instead, Kepler discovered its importance in explaining the elliptical path of the planets
and moon, varying speed of planets motion and the harmony of the distance of the
planet and its motion. Which was later called Kepler's Laws of Planetary Motion.
 First Law:
Law of Ellipse
 Second Law: Laws of Equal Areas
 Third Law:
Law of Period
14
Assessment (Post Test)
Multiple Choices. Select the letter of the best answer from among the given choices.
1. Which of the observations below was used by Aristotle to prove his claim that Earth is not
flat?
A. He noticed that all things seem to be moving around the Earth except for Earth itself
B. He argued that since the shape of the moon appears to be round then the Earth
must also be round.
C. He argued that lunar eclipse only happens when a round opaque object blocks the
passage of sunlight.
D. He noticed that during a lunar eclipse the shadow casts by Earth on the moon is
round.
.
2. Which of the statements below refers to the information gathered by Eratosthenes about a
phenomenon that happened at the same date and time during the summer solstice in
Seyene and Alexandria?
A. In Seyene, sunlight shines directly down a deep well and is reflected back, while in
Alexandria the vertical pillar did not cast a shadow at all.
B. In Seyene, a vertical pillar cast a shadow, while in Alexandria sunlight shines
directly down a deep well and is reflected back.
C. In Seyene, sunlight shines directly down a deep well and is reflected back, while
in Alexandria the vertical pillar cast a shadow.
.
D. Both in Seyene and Alexandria that the structures cast a shadow.
3. Which of the following is also presented by the Greeks to prove that the Earth is spherical?
A. solar eclipse
B. sunrise and sunset
C. ships sailing seemed to be gradually disappearing in the horizon
D. passing of the comet in Earth’s orbit
4. Aside from Aristotle who among the philosophers below believed that Earth is spherical?
A. Pythagoras and the Mesopotamians
B. Pythagoras and Plato
C. Plato and the Mesopotamians
D. Mesopotamians and Egyptians
5. Based on Eratosthenes' calculation, the circumference of the Earth is equivalent to
A. 250 000 stadia
B. 5 000 stadia
C. 2 500 000 stadia
D. 500 000 stadia
.
6. Which phase of the moon is shown in the figure?
A. full moon
B. new moon
C. first quarter moon
D. last quarter moon
7. The following are astronomical phenomena that were already observed by the ancient
people even before the telescope was invented except
.
A. solar eclipse
B. phases of the moon
C. craters of the moon
D. planet like Venus
8. Which of the statements below describes a lunar eclipse?
A. A lunar eclipse occurs when the Earth is behind the Sun and the moon is in front
of the Sun.
B. A lunar eclipse occurs when the moon is between the Earth and the Sun
C. A lunar eclipse occurs when the moon is forming ninety degree-angle with the Earth.
D. A lunar eclipse occurs when the Earth is between the moon and the Sun.
15
9. Based on the observation made by ancient astronomers, the Sun rises in the
and sets in the
direction.
A. west, east
B. south, west
C. north, south
D. east, west
10. Refer to the figure below, “phases of the moon”. Which among the numbered figure
represents the full moon?
A. 1
B. 2
C. 3
D. 4
11. The accurate measurement of the positions and distances of stars and planets in
themajor contribution of
to the field of astronomy.
A. Johannes Kepler
B. Tycho Brahe
C. Copernicus
D. Ptolemy
12. Below is Brahe’s model of the universe. What is the implication
of Brahe’s model when it comes to the idea of the center of the
universe?
A. There are two centers the Earth and the Sun.
B. The Earth, not the Sun is the center of the universe.
C. The Sun, not the Earth is the center of the universe.
D. Neither the Earth nor the Sun is the center of
theuniverse
13. Based on Kepler's First Law, which of the figures below describes the path of a
planetas it moves around the Sun?
A
B
C
D
14. Kepler discovered that planets do not go around the Sun at a uniform speed but it
depends on its position relative to the Sun. What is its speed when it is farther from
the Sun?
A. faster
B. neither fast nor slow
C. slower
D. similar to the speed when it is closer to the Sun
15. Kepler’s third law of planetary motion states that the ratio of
.
A. the cube of the times of revolution of the planets are proportional to the
squareof their average distance from the Sun.
B. the cube of the times of revolution of the planets is not proportional to the
squareof their average distance from the Sun.
C. the square of the times of revolution of the planets is proportional to the
cube of their average distance from the Sun.
D. the square of the times of revolution of the planets is not proportional to the
cubeof their average distance from the Sun.
niSoenioirgH
higSh S
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Physical Science
Quarter 2 - Module 2
The Laws of Physics
Table of Contents
What This Module is About ................................................................................................. i
What I Need to Know .......................................................................................................... ii
How to Learn from this Module ........................................................................................... ii
Icons of this Module ............................................................................................................ iii
What I Know ....................................................................................................................... iv
Lesson 1: The Concept of Motion .............................................. 1
What I Need to Know ...................................................................................1
What’s New: Find Me..............................................................................................1
What Is It: The Concept of Motion ................................................................2
What’s More: Aspects of Motion ...........................................................................4
What I Have Learned: Let’s Compare ..................................................................5
What I Can Do: You Complete Me ...............................................................5
Lesson 2: Uniform Acceleration ................................................. 6
What’s In ...................................................................................................................6
What I Need to Know ...................................................................................6
What’s New: I Belong ............................................................................................. 6
What Is It: Uniform Acceleration ................................................................... 7
What’s More Free Fall ............................................................................................ 9
What I Have Learned: Caption Time ........................................................... 10
What I Can Do: My Ball ............................................................................... 10
Lesson 3: Cause of Motion .......................................................... 11
What’s In ...................................................................................................................11
What I Need to Know ...................................................................................11
What’s New: Count Me In ...................................................................................... 11
What Is It: Cause of Motion .......................................................................... 12
What’s More: Inertia in Motion............................................................................... 12
What I Have Learned: Be Organized ............................................................ 13
What I Can Do: Photos of the Day ............................................................... 14
Summary ............................................................................................................................ 14
Assessment: (Post-Test) .................................................................................................... 15
Key to Answers ................................................................................................................... 17
References ......................................................................................................................... 19
What This Module is About
Welcome to the Physical Science Self Learning Module. This material will sharpen
your understanding of Mechanics—the study of motion and its causes. This will enable you to
explore a variety of activities diverging concepts of the laws of physics. These universal laws
always apply under the same conditions and imply that there is a causal relationship involving
its elements. Discover these laws of Physics and you will sharpen your intuition of nature!
This module covers the following lessons:
Lesson 1: The Concept of Motion
Lesson 2: Uniform Acceleration
Lesson 3: The Cause of Motion
What I Need to Know
At the end of this module, you should be able to:
1. Compare and contrast the Aristotelian and Galilean concepts of vertical motion,
horizontal motion, and projectile motion. (S11/12PS-IVc-46)
2. Explain how Galileo inferred that objects in vacuum fall with uniform acceleration, and
that force is not necessary to sustain horizontal motion (S11/12PS-IVc-47)
3. Explain the subtle distinction between Newton’s 1st Law of Motion (or Law of Inertia)
and Galileo’s assertion that force is not necessary to sustain horizontal motion
(S11/12PS-IVd-51)
How to Learn from this Module
To achieve the objectives cited above, you are to do the following:
.1. Carefully read and follow instructions.
2. As a courtesy to the future users of this module, PLEASE DO NOT WRITE
ANYTHING ON ANY PART OF THIS MODULE. Write your answer/s on a
separate sheet of paper, notebook, workbook or whichever is specified by your
facilitator.
2. Take the pretest--a simple multiple-choice test provided at the start to
determine how much you know about the content of this module. Be very honest in
taking the test so you will know how much knowledge you already have about the
topic.
5. Read all lessons included in this module.
6. Perform all the activities diligently, as these will help you have a better
understanding of the topic. When you need help, tap your parent/guardian, facilitator
or contact your subject teacher.
7. At the end of each lesson, take the self-tests to determine how much did you learn
with the concept and applications. Cultivate your integrity by doing what is right even
if no one is watching.
8. Eventually, take the post-test at the end of this module.
i
Icons of this Module
Here are the Icons used as your guide in every part of the lesson:
What I Need to
Know
This part contains learning objectives that
are set for you to learn as you go along the
module.
What I know
This is an assessment as to your level of
knowledge of the subject matter at hand
meant specifically to gauge prior related
knowledge
What’s In
This part connects the previous lesson with
that of the current one.
What’s New
An introduction to the new lesson through
various activities, before it will be presented
to you
What is It
These are discussions of the activities as a
way to deepen your discovery and
understanding of the concept.
What’s More
These are follow-up activities that are
intended for you to practice further to master
the competencies.
What I Have
Learned
Activities designed to process what you have
learned from the lesson
What I can do
These are tasks that are designed to
showcase your skills and knowledge gained
and applied to real-life concerns and
situations.
ii
What I Know
Multiple Choice. Select the letter of the best answer from among the given choices.
1. What is the force required to maintain an object at a constant velocity in a frictionless
surface equal to?
A. zero
B. the mass of the object
C. the weight of the object
D. the force required to stop it
2. When does an object undergo acceleration?
A. when it is changing direction
B. when it is moving faster
C. when it is moving slower
D. all of these
.
3. A ball is thrown upwards and returns to the same location. When it turns, how much is
the speed compared with the initial speed?
A. half as much
B. the same
C. twice as much
D. four times as much
4. How does Galileo's interpretation of motion differ from Aristotle's? Galileo emphasized
A. rates of time
B. the acceleration of free fall
C. the role of distance in describing motion
D. none of these
5. From what you have learned from Galileo, what will happen if you roll a ball along a
level surface?
A. keep rolling if friction is absent
B. roll as long as its inertia nudges it along
C. soon roll in the opposite direction
D. soon slow down due to its natural place
6. What is the straight-line motion caused by the gravitational pull of the earth?
A. free-fall motion
B. horizontal motion
C. projectile motion
D. none of these
.
.
7. How does the acceleration of a stone thrown upward compare to the one thrown
downward?
A. greater
B. smaller
C. the same
D. undetermined
8. What will happen to an object if no external forces act on it?
A. It will come to an abrupt halt.
B. It will continue moving at the same speed.
C. It will move slower and slower until it finally stops.
D. None of these
9. When no forces act on moving objects on-air, how can you describe their paths?
A. circles
B. ellipses
C. parabola
D. straight lines
10. Suppose you are riding a motorcycle, but it runs out of fuel while driving. The engine
stops abruptly but why don't you?
A. because of gravity
B. because of inertia
C. because of continuation principle D. because of resistance
iii
11. Suppose you are standing in the aisle of a moving bus. If the driver suddenly makes
a left turn, why are you likely to lurch to the right? Because of
A. an equilibrium challenge
B. an unbalanced force
C. your momentum
D. your tendency to keep moving forward
12. Which of the following best describes an accelerating object?
A. object at rest
B. object in mechanical equilibrium
C. object moving at constant velocity D. object moving slower
13. A ball rolling along a horizontal surface maintains a constant speed. Why is it so?
A. friction is present
B. no inertia on the object
C. no horizontal force acts on it
D. surface is smooth
14. Why do a coconut and a bird's feather falling from a tree through the air to the ground
below gain speed?
A. their velocity changes
B. there is a gravitational force acting on them
C. their inertia
D. their nature to become closer to the Earth
15. Which of the following is true about acceleration due to gravity?
A. it is different for different objects in free-fall
B. It is a fundamental property
C. It increases in decreasing altitude
D. it is a universal constant
iv
Lesson
The Concept of Motion
1
What I Need to Know
A lot of Physics can be observed in daily activities. Motion occurs all around you. It
refers to a change in a position of any mass with respect to time. It’s easy to recognize but
hard to describe. A motion has held the attention of scientists and philosophers since ancient
times.
In this lesson, you will be able to compare and contrast Aristotelian vs. Galilean views
of vertical motion, horizontal motion, and projectile motion.
What’s New
Activity 2.1.1 Find Me
Encircle five words which relate to motion. The words can be read horizontally,
vertically and diagonally. 1 point each
F
P
O
E
F
S
T
B
G
H
R
E
G
T
E
R
A
S
R
T
U
I
O
M
G
R
F
C
C
O
E
N
D
U
H
O
N
E
S
R
Y
G
A
J
T
E
F
T
A
D
W
V
Q
O
M
M
M
E
H
E
F
H
U
E
D
E
S
S
E
I
N
C
C
C
L
A
T
L
E
R
F
T
N
S
T
T
A
C
C
E
L
E
R
A
T
I
O
N
R
I
V
E
L
V
E
L
O
C
I
T
Y
T
1
S
L
O
E
F
S
T
B
G
H
N
E
G
T
T
E
J
V
I
C
P
E
H
G
J
C
R
R
L
M
Y
E
C
F
I
E
Y
N
R
V
F
I
O
S
B
S
A
R
Y
O
E
J
T
S
C
B
A
S
R
T
U
I
O
M
G
D
I
C
N
E
C
R
E
H
G
I
C
R
R
V
Z
O
W
V
What Is It
The motion of objects has been studied since ancient times. Let us take a look at the
past for a thorough understanding of the motion concepts at the present.
Aristotle thought that heavy objects fall faster than light objects in proportion to their
weight. Galileo argued that the motion of a falling body should be nearly dependent on its
weight and should have constant acceleration through careful measurements of distances and
time experiments.
Several physical quantities help described the motion of objects. Here are some of
them:
Physical
Quantity
Distance
Table 2.1.1 Physical Quantities in Describing Motion
Symbol
Description
Working Equation
d
Displacement
length of the part
travelled from starting
point to final point
m
length of the
travelled from
starting point to
final
point
consideration to
direction
m

Speed
𝑣
S. I.
Unit
part
the
the
with
the
arrow indicates direction
the rate at which
distance is covered
𝑠𝑝𝑒𝑒𝑑 =
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑖𝑚𝑒 𝑖𝑛𝑡𝑒𝑟𝑣𝑎𝑙
v
Velocity
𝑣
the displacement in a
given time interval
Acceleration
𝑎
a measure of how fast
the velocity changes
with respect to time.
𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 =
𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 =
d
t
m
s
𝑑𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡
𝑡𝑖𝑚𝑒 𝑖𝑛𝑡𝑒𝑟𝑣𝑎𝑙
m
s
𝑐ℎ𝑎𝑛𝑔𝑒 𝑜𝑓 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦
𝑎=
𝑡𝑖𝑚𝑒 𝑖𝑛𝑡𝑒𝑟𝑣𝑎𝑙
∆𝑣
m
s2
∆𝑡
Aristotle and Galileo were two of the most important historical figures that laid the
foundation of motion concepts. Their views regarding motion may be opposite but both helped
the progress of science.
2
Table 2.1.2 Aristotle vs Galileo’s Concept of Motion
Motion
Horizontal
motion
Aristotelian Concept
Galilean Concept
Force is required to maintain
horizontal motion.
Objects moving in a straight line at
a constant speed requires no force
to keep them moving.
All moving bodies naturally come to
rest
Vertical
motion
It will continue in motion due to
inertia unless an external force acts
on them.
A. Freefall is a natural motion
occurring due to the tendency of
nature to established balance to
bring disturbing elements to its
natural resting place.
A. Objects move downward
because gravity disturbs their
motion.
B. Heavier objects have more
earthly elements than lighter ones
hence they should fall faster and
will take a shorter time to reach
the ground
B. The rate of fall or acceleration of
an object is independent of its
mass.
C. The motion of falling objects is
uniformly accelerated.
C. Warmer bodies have access to
fiery elements hence they ascend
faster.
Projectile
motion
The motion of a projectile is parallel
to the ground until it is the object's
time to fall back into the ground.
A projectile moves two-dimensional
motion in a parabolic path
The horizontal motion component
has zero acceleration (constant
speed horizontally) and vertical
acceleration is constant.

Free fall-a body in vertical motion where only gravity is acting on it. It could be an object
thrown upward (positive initial velocity), thrown downward (negative initial velocity) or
dropped (zero initial velocity).

Projectile- a body or a particle in
two-dimensional motion given an
initial velocity and it
moves
along a curved path under the
influence of gravity alone (see figure
a)
Figure 1. Projectile’s trajectory
In recent times, the motion of falling bodies has been studied with great precision.
When air resistance can be neglected, all bodies experience equal acceleration regardless of
their size and weight. This constant acceleration g is called the acceleration due to gravity.
The standard value of g at or near the earth’s surface is approximately 9.8 m/s2.
3
What’s More
Activity 2.1.2 Let the Coin Move!
Perform the following activity to help you acquire more understanding of motion
concepts. Collaborate with one or two of your housemates, use indigenous materials
whenever possible and keep safe all the time. Submit a complete report.. (Criteria: critical
thinking-15, collaboration-5, communication-5)
I. Objective: Explain the relationship between speed and acceleration
II. Materials: 2 pcs identical coins, timer, table
III. Drawing of the Set-up:
IV. Procedure:
A. Horizontal Motion
1. Label the coins A and B.
2. Place coin A 1 foot (0.30m) from coin B on the smooth tabletop. With your timer on
your left hand (if you are right-handed), slide coin A across the table (such as by
flicking with your finger using your other hand) so that it strikes coin B. Sliding the
coin and turning on the timer must be done simultaneously. Observe the motion
closely and stop the timer when coin A hits B. Complete Table 2.1.3.
Parameter
Time
Distance
Displacement
Speed
Velocity
Table 2.1.3 Horizontal Motion Description
Complete Answer
3. Answer the questions:
A. Is coin A moving slower or moving faster?
B. Is it accelerating?
B. Projectile Motion
1. Place coin B at the edge of the tabletop so that it hangs over slightly.
2. Place a coin A on the same tabletop some distance from the overhanging coin B.
3. Flick coin A so that it strikes the overhanging coin B and both coins fall to the floor
below. Observe which coin hit the ground first and record Table 2.1.4 number 1.
4. Repeat Steps 2-3 but this time flick coin A harder so that it will have greater speed
as it strikes coin B. Complete the table.
Table 2.1.4 Initial Velocity and Acceleration due to Gravity
Trial
Which Coin Hit the Ground First
1. Flicking coin A to hit coin B
2. Flicking coin A harder to have
greater speed in hitting coin B
4
V. Conclusions:
VI. Guide Questions:
1. Does the landing of both coins on the floor depend on the speed of the sliding
coin? Explain.
2. What is the relationship between speed and acceleration?
What I Have Learned
Activity No. 2.1.3 Let’s Compare!
Using the Venn Diagram, compare and contrast Aristotle and Galileo's concept of
vertical, horizontal and projectile motion.
What I Can Do
Activity 2.1.4 You Complete Me
Give an example of other real-life applications of motion by completing the table. The
first item is done for you. 1 point each
Table 2.1.5. Conceptual Application of Motion
Type of Motion
Application
the
motion
of
water
coming out from a hose you hold
Projectile Motion
when watering plants in your yard
Horizontal Motion
Free-Fall Motion
Projectile Motion
5
Lesson
Uniform Acceleration
2
What’s In
Galileo Galilei having the insight and talent to link theory with the experiment was
regarded as the father of modern science. He did many experiments on the concept of Freefall.
What I Need to Know
In this lesson, you will be able to explain how Galileo inferred that objects in vacuum
fall with uniform acceleration and that force are not necessary to sustain horizontal motion.
What’s New
Activity 2.2.1 I BELONG
Unscramble the words related to uniform acceleration. Write down your answers in the
box. 1 point each
1. EFER LFLA
2. AIGVRYT
3. ARTIGSHT EINL
4. CRJLTOPEEI
5. UAUCVM
6
What Is It
Objects in Vacuum Fall with Uniform Acceleration
Galileo was interested in the behavior of falling objects. He knew that as falling objects
go down, they increase their speed as they go down. This change in speed is acceleration.
Although he did not have any tool to measure this change, so he used inclined planes to
reduce the acceleration of the moving bodies. He was then able to take a close look at the
moving bodies carefully.
With his experiments, Galileo proved that regardless of their masses and air
resistance, two objects dropped simultaneously will reach the ground at the same time. He
also discovered that objects fall with uniform acceleration.
What is uniform or constant acceleration?
For Galileo, constant acceleration means moving with increasing velocity evenly
proportionate to time. The following graphs show the comparison between the motion of
objects with constant velocity and object with constant acceleration.
Figure 2. Comparison Between Constant Velocity and Constant Acceleration
Positive velocity-indicates the object moves toward the positive direction
Negative velocity- indicates the object moves toward the negative direction
Positive acceleration-indicates the object is speeding up
Positive acceleration-indicates the object is slowing down
In one of his experiment on the inclined plane, Galileo’s was able to gather the data as
shown in Table 2.2.1
Table 2.2.1. Galileo’s Data on a Free Fall Experiment
Time (s)
0
1
2
3
4
6
Speed (m/s)
0
2
4
6
8
10
Acceleration (m/s2)
≈2
≈2
≈2
≈2
≈2
After every second, a ball rolling down an inclined plane increases its speed by the same
value. He then observed the following;
 acceleration of the rolling ball increases as the inclined plane becomes steeper.
 When the inclined plane was positioned vertically, the rolling ball has maximum
acceleration.
7
To have a constant velocity, an object must have a constant speed in a constant
direction. If an object maintains a constant or a uniform change in its velocity in a given time
interval along a straight line, then it is said to have a constant acceleration.
Force is Not Necessary to Sustain Horizontal Motion
While Aristotle believed that forces are necessary to keep objects in motion. Galileo’s
believe otherwise although a force is needed to start an object moving, Galileo believed that
force was not necessary to sustain motion and did this experiment:
Figure 3. Galileo’s Experiment on Sustaining Motion
Galileo rolled balls down inclined planes and observed and recorded the gain in speed
as the rolling continued. On downward-sloping planes, the force of gravity increases a ball’s
speed while on an upward slope, the force of gravity decreases a ball’s speed. If smoother
planes were used, the ball rolled up the opposite plane closer to the initial height. The
difference between initial and final heights was because of friction. He postulated the ball
would reach the same height if friction could be eliminated.
With regards to the ball rolling on a level surface, it neither slows down nor speeds up.
It maintains a constant speed. Galileo reasoned that a ball would move forever if it is in a
horizontal motion. If friction were absent once it is moving, no force is needed to keep it moving
except for the force needed to overcome friction. A moving object needs no force to keep it
moving. when friction is absent. Such a ball would remain in motion all by itself of its inertia.
8
What’s More
Activity 2.2.2
FREE FALL
Perform the following activity to help you acquire more understanding of the free-fall
concept. Collaborate with one or two of your housemates, Use indigenous materials whenever
possible and keep safe all the time. Submit a complete report. (Criteria: critical thinking-15,
collaboration-5, communication-5)
I. Objective: Explain uniform acceleration
II. Materials: 2 pcs of used bond paper (any paper of the same size), old notebook, coin
III. Drawing of the Set-up:
IV. Procedure:
1. Crumple up one piece of paper.
2. Hold the piece of paper in one hand and the crumpled paper in another hand at about
a meter from the ground. Drop them simultaneously. Which falls to the ground faster?
A record at Table 2.2.2
3. Hold a piece of paper and a notebook at the same height. Drop them simultaneously.
Which falls to the ground faster? Paper or notebook?
4. Repeat Step 2 but this time pair the piece of paper with a coin. Complete the table.
5. Repeat Steps 2-4 but this time at a higher height (caution: safety first).
Table 2.2.2. Size and Acceleration Due to Gravity
Pair of Objects
If no, which falls to
the ground first?
Do the two objects
reach the ground at
the same time?
[Yes/No]
What if you do the
same activity more
than 1m above the
ground?
Piece of Paper
and Crumpled
paper
Piece of Paper
and Notebook
Piece of Paper
and Coin
IV. Conclusions:
V. Guide Questions
1. Answer the question: What factors affect the fall of the object? Justify your
answer.
2. What is uniform acceleration?
9
What I Have Learned
Activity 2.2.3 Caption Time
Place your detailed caption below the image to infer Galileo’s explanation on motion
concepts: Choose from the following;
 objects in vacuum fall with uniform acceleration
 force is not necessary to sustain horizontal motion.
1.
2.
What I Can Do
Activity No. 2.2.4 My Ball
Throw a ball upward. Observe closely. Why does the ball not hang there forever? Write
your observation on a clean sheet of paper.
10
Lesson
Cause of Motion
What’s In
In the previous lessons, we learned how to describe motion. Galileo’s achievements in
the study of motion paved way for Newton in his development of the laws of motion. What
causes changes in motion? Applied force, you may say, but is that so?
What I Need to Know
In this lesson, you will be able to explain the subtle distinction between Newton’s 1st
Law of Motion (Law of Inertia) and Galileo’s assertion that force is not necessary to sustain
horizontal motion.
What’s New
Activity 2.3.1 Count Me In
Check the box of the word/phrases as an application of the Law of Inertia. 1 point each
1. An ABM book/business ledger sliding across the working table slows
down and stops
2. Headrest placed in cars
3. A HUMSS research group walking from the house to the Baranggay Hall to conduct
a survey
4. A ball rolling in the basketball court during PE class of Grade 11 GAS
5. TVL work immersion students riding an accelerating public utility jeepney
11
What Is It
For many years, the accepted opinion was Aristotle’s concept that moving objects
would stop because the natural state of objects was to be at ‘rest’. However, as for Galileo,
once the ball is in motion, no force is needed to keep it moving except for the force needed to
overcome friction. Friction is an opposing external force that prevents its continued motion. A
moving object needs no force to keep it moving when friction is absent. It will remain in motion
all by itself. All objects tend to resist changes in motion. This means they all have inertia.
Sir Isaac Newton made a great revolution in the growth of Science primarily in Physics
with his famous Laws of Motion. He built these concepts on Galileo’s concept of inertia. He
established a new set of ideas with his three (3) Laws of Motion that includes the 1st Law of
Motion, more popularly known as the Law of Inertia. It states:
“An object at rest remains at rest and an object in motion remains in motion in a straight
line with a constant speed unless an external force acts on it.”
This means that things tend to keep on doing what they are already doing. Notebooks on top
of the table are in a rest state, they tend to stay at rest even when you quickly snap the
tablecloth or paper underneath. If you slide a coin along the road, the coin soon comes to rest.
If you let it slide along a frictionless surface such as an ice rink, it continuously moves. A
moving object tends to move in a straight line indefinitely in the absence of a force.
. The object’s resisting changes in its state motion depends upon its mass. The more
mass the object has, the greater is the tendency to resist changes in motion
What’s More
Activity 3.3.2 Inertia in Motion
Perform the following activity to help you acquire more understanding of the inertia
concept. Collaborate with one or two of your housemates, Use indigenous materials whenever
possible and keep safe all the time. Submit a complete report. (Criteria: critical thinking-15,
collaboration-5, communication-5)
I. Objective: Explain Newton’s First Law of Motion
II. Materials: ball, clearly-marked target (i.e., notebook paper, tape measure or ruler)
III. Drawing of the Set-up:
IV. Procedure:
1. Mark a starting point and target point, A and B, respectively, six meters (about 20 ft)
away from each other. Mark also C, 1 meter (3.28 ft) before the target (B) and mark D
1 meter after the target.
12
2. With the ball in your hand, you are about to sprint towards the target (B) respectively
and to drop the ball on it. Record your predictions on table 2.3.1.
3. Hold the ball and do not let your elbow leave your side as you sprint toward the target
and drop the ball. Do not give the ball an initial velocity; hold the ball from its sides so
that you can freely release your grip as you let it drop.
4. Record where the runner released the ball and where the ball strikes the ground.
Table 2.3.1. Verifying Motion Prediction
Prediction
Actual
(What will
(What
happen?)
happened?)
1. Running in full sprint
2. Running at reduced speed
3. Walking speed
Motion
Remarks
5. Draw the best diagram for each attempt to drop the ball on the target. Specify where the
ball was released and where it landed.
6. Repeat the experiment until the ball hits the target.
7. Repeat steps 2-5 but this time, do not sprint, just run at a slower speed. Record your
observation in Table 2.3.1.
8. Repeat step 7 but at a walking speed. Record your observation in Table 2.3.1.
V. Conclusions
VI. Guide Question:
How will you relate today’s activity with Newton's First Law of Motion and with inertia?
What I Have Learned
Activity 2.3.3 Be Organized
Create a graphic organizer to present a subtle distinction between Newton's Law
of Inertia and Galileo’s assertion that force is not necessary to sustain horizontal motion.
(Critical Thinking-5, Communication 5, Creativity 5)
13
What I Can Do
Activity 2.3.4 Photos of the Day (Criteria: Critical Thinking-5, Communication 5, ICT-5)
1. Take pictures with you or your family featuring different Newton’s Law of Inertia.
Choose the best three photos.
2. Find a friend on Facebook Messenger or somebody at home. Share with him for 2
minutes what you have learned about the subtle distinction between Newton's Law of
Inertia and Galileo's assertion that force is not necessary to sustain horizontal motion.
3. Encourage the person to ask 2-3 questions about what you have shared. If he has no
questions, you may ask him these:
a. Where can you use the concept and skills I have shared with you today in your
daily life?
b. Why is it important to know the Law of Inertia?
c. How can you develop desirable values and traits in life (i.e. respect, helpfulness,
critical thinking, etc.) with the topic that I have shared?
Record questions and answers.
4. Show him the pictures that you have taken one at a time and ask him if those pictures
describe the Law of Inertia.
5. Send screenshots or submit a related output to your teacher.
Summary
 An object is in motion when it changes position with respect to a reference point.
 Velocity consists of an object’s speed and direction.
 Acceleration is a change in an object’s velocity.
 Objects in a vacuum fall with uniform acceleration regardless of mass.
 Force is not necessary to sustain horizontal motion.
 Newton’s First Law of Motion states that an object at rest remains at rest and an object in
motion remains in motion in a straight line with a constant velocity unless an external force
acts on it.
14
Assessment (Posttest)
Multiple Choice. Answer the question that follows. Choose the best answer from among
the given choices.
1. What is the straight-line motion caused by the gravitational pull of the earth?
A. free-fall motion
B. horizontal motion
C. projectile motion
D. none of these
.
.
2. How does the acceleration of a stone thrown upward compare to the one thrown
downward?
A. greater
B. smaller
C. the same
D. undetermined
3. What will happen to a moving object if no external forces act on it?
A. It will come to an abrupt halt.
B. It will continue moving at the same speed.
C. It will move slower gradually until it stops.
D. none of these
4. When no forces act on moving objects on-air, how can you describe their paths?
A. circles
B. ellipses
C. parabola
D. straight lines
5. Suppose you are riding a motorcycle but it runs out of fuel while driving. The engine
stops abruptly but why don't you?
A. because of gravity
B. because of inertia
C. because of continuation principle
D. because of resistance
6. Suppose you are standing in the aisle of a moving bus. If the driver suddenly makes a
left turn, why are you likely to lurch to the right? Because of
A. an equilibrium challenge
B. an unbalanced force
C. your momentum
D. your tendency to keep moving forward
7. Which of the following best describes an accelerating object?
A. object at rest
B. object in mechanical equilibrium
C. object moving at constant velocity
D. object moving slower
8. A ball rolling along a horizontal surface maintains a constant speed. Why is it so?
A. friction is present
B. no inertia on the object
C. no horizontal force acts on it
D. surface is smooth
9. Why do a coconut and a bird's feather falling from a tree through the air to the ground
below gain speed?
A. their velocity changes
B. there is a gravitational force acting on them
C. their inertia
D. their nature to become closer to the Earth
15
10. Which of the following is true about acceleration due to gravity?
A. It is different for different objects in free-fall.
B. It is a fundamental property.
C. It increases in decreasing altitude.
D. It is a universal constant.
11. Which of the following statements is true?
A. A body can have a constant direction but varying speed and still be accelerating
B. A body can have a constant speed but varying direction and still be accelerating
C. A body can have varying speed and direction and still be accelerating
D. All of these
12. When does an object undergo acceleration?
A. when it changes its direction
B. when it gains speed
C. when it loses speed
D. all of these
.
13. A ball is thrown upwards and returns to the same location. When it returns, how muchis
the speed compared with the initial speed?
A. half as much
B. the same
C. twice as much
D. four times as much
14. How does Galileo's interpretation of motion differ from Aristotle's? Galileo
emphasized
A. rates of time
B. the acceleration of free fall
C. the role of distance in describing motion
D. none of these
15. From what you have learned from Galileo, what will happen if you roll a ball along alevel
surface?
A. keep rolling if friction is absent
B. roll as long as its inertia nudges it along
C. soon roll in the opposite direction
soon slow down due to its natural place
16
nioighigSh S
hohool ol
Physical Science
Quarter 2 - Module 3
Light as a Wave and as a Particle
17
Table of Contents
What This Module is About ................................................................................................... i
What I Need to Know ............................................................................................................ i
How to Learn from this Module ............................................................................................. ii
Icons of this Module .............................................................................................................. ii
What I Know ........................................................................................................................ iii
Lesson 1:
The Nature of Light
What I Need to Know .................................................................................... 1
What’s New: Observing a Ball’s Path at Different Speed ................................... 1
What Is It: Theories of Light .......................................................................... 1
What’s More: Exploring How Light Travels .......................................................... 3
What I Have Learned: Sharing my Insights ................................................... 3
What I Can Do: Reflecting Me ....................................................................... 3
Lesson 2:
Energy of Light
What’s In ....................................................................................................... 4
What I Need to Know .................................................................................... 4
What’s New: Arranging Rainbow Colors .............................................................. 4
What Is It: Energy and Frequency of Light ..................................................... 4
What’s More: Matching Perfectly ............................................................................. 6
What I Have Learned: Writing it Right .................................................................... 6
What I Can Do: Spotting Similarities and Differences .......................................... 6
Lesson 3:
Wave-like Properties of Electron
What I Need to Know .................................................................................... 7
What’s In .................................................................................................................... 7
What’s New: Let’s Match History............................................................................ 7
What Is It: Can Electrons Behave Like Waves ............................................... 8
What’s More: Where Can I Find You ...................................................................... 8
What I Have Learned: Let Me Test Myself ............................................................ 9
18
What I Can Do: Challenge The Scientist in Me .................................................... 9
Lesson 4:
Properties of Light
What’s In .................................................................................................................... 10
What’s New: Am I Dispersed ................................................................................. 10
What a Colorful Day .................................................................................................... 10
What Is It: Dispersion & Scattering of Light .................................................... 10
What’s More: Let Me Interfere ................................................................................. 12
Let Me See You Through ............................................................................................... 12
What Is It: Interference & Diffraction of Light .................................................. 12
What I Have Learned: You Complete Me .............................................................. 13
What I Can Do: Let Me be a Collector................................................................... 13
Lesson 5:
Various Light Phenomena
What’s In .................................................................................................................... 14
What I Need to Know .................................................................................... 14
What’s New: My Spoony Image/May I Pass Through......................................... 14
What Is It: Why Optical Phenomena Happen ................................................. 15
What’s More: Picture Analysis ................................................................................. 16
What is It: Various Light Phenomena ............................................................. 16
What I Have Learned: Let’s Test Your Understanding ........................................ 17
What I Can Do: Let’s Illustrate ................................................................................ 17
Lesson 6:
HERTZ’S RADIO PULSES
What’s In ......................................................................................................................18
What I Need to Know ..................................................................................... 18
What’s New: Find Me Clearly.................................................................................. 18
What Is It: Hertz’s Apparatus ................................................................................... 19
What’s More: Hertz’s Experiment ................................................................... 19
What I Have Learned: Test Your Memory ............................................................. 20
What I Can Do: Research Time............................................................................... 20
Summary ............................................................................................................................................... 20
Assessment .......................................................................................................................... 21
Key to Answers ..................................................................................................................... 23
19
References ........................................................................................................................... 26
20
What This Module is About
We live in a colorful world. The green leaves of trees, the blue lakes and oceans, the
white clouds, the red-orange horizon, the colorful rainbow, the multicolored landscape to name
a few. We see these wonderful creations because of the presence. of light. Would it be
wonderful to know the science behind all these?
In this module, you will be introduced to the dual nature of light, its properties and
behavior, and the various optical phenomena created by light. It includes light being a particle
and a wave or both. Some properties of light can be explained by considering light as a wave
(interference of light, diffraction and scattering) while other properties can be explained by
considering light as a particle (photoelectric effect) and still others can be explained
considering light as both wave and particle (reflection, refraction and dispersion). It also
includes the wave-like characteristics of electron and how Hertz produced radio pulses
applying the evidence-based knowledge of his predecessors on light and electron.
Quite interesting! You may now start exploring this module.
The following are the lessons contained in this module:
1. The Nature of Light
2. Energy of Light
3. Wave-Like Property of Electron
4. Properties of Light
5. Various Light Phenomena
6. Hertz's Radio Pulses
What I Need to Know
At the end of this module, you should be able to:
1. Describe how the propagation of light, reflection, and refraction are explained by the
wave model and the particle model of light (S11/12PS-IVf-59);
2. Explain how the photon concept and the fact that the energy of a photon is directly
proportional to its frequency can be used to explain why red light is used in
photographic darkrooms, why we get easily sunburned in ultraviolet light but not in
visible light, and how we see colors (S11/12PS-IVf-61);
3. Cite experimental evidence showing that electrons can behave like waves (S11/12PSIVf-6);
4. Differentiate dispersion, scattering, interference, and diffraction (S11/12PS-IVf-65)
5. Explain various light phenomena such as:
A. Your reflection on the concave and convex sides of a spoon looks different
B. Mirages
C. Light from a red laser passes more easily through red cellophane than green
cellophane
D. Clothing of certain colors appear different in artificial light and in sunlight
E. Haloes, sundogs, primary rainbows, secondary rainbows, and supernumerary bows
F. Why clouds are usually white and rainclouds
dark
21
G. Why the sky is blue and sunsets are red (S11/12PS-IVf-66)
6. Describe how Hertz produced radio pulses (S11/12PS-IVf-68)
i
How to Learn from this Module
To achieve the objectives cited above, you are to do the following:
•
•
•
•
•
•
Get your pen and journal ready.
Take your time reading the lessons carefully note-taking important information and
keywords.
Follow the directions and/or instructions in the activities and exercises diligently.
Perform the activities to heart. Write your observations in your journal.
Answer all the given tests and exercises as honestly as possible.
If you have any questions for clarification, feel free to consult your teacher.
Icons of this Module
What I Need to
Know
This part contains learning objectives that
are set for you to learn as you go along the
module.
What I know
This is an assessment as to your level of
knowledge to the subject matter at hand,
meant specifically to gauge prior related
knowledge
What’s In
This part connects the previous lesson with
that of the current one.
What’s New
An introduction of the new lesson through
various activities, before it will be presented
to you
What is It
These are discussions of the activities as a
way to deepen your discovery and
understanding of the concept.
What’s More
These are follow-up activities that are
intended for you to practice further in order to
master the competencies.
What I Have
Learned
Activities designed to process what you have
learned from the lesson
These are tasks that are designed to
showcase your skills and knowledge gained,
and applied into real-life concerns and
situations.
22
What I can do
ii
What I Know
Multiple Choice. Select the letter of the best answer from among the given choices.
1. Which of the following phenomena describes no difference between the wave
theoryand particle theory of light?
A. diffraction
C. reflection
B. interference
D. refraction
2. Which factor remains constant when light travels in a different medium?
A. Color
C. Speed
B. Frequency
D. Wavelength
3. Why does a blue t-shirt appear blue?
A. Blue is absorbed by the t-shirt
C. Blue is reflected by the t-shirt
B. Blue is emitted by the t-shirt
D. Blue is refracted by the t-shirt
.
4. E=hf is an equation that describes the relationship between energy (E) and frequency of
light (f). What will happen to the energy of light as the frequency goes higher? It
A. goes higher
C. remains the same
B. goes lower
D. undetermined
5. Under which type of light do we easily get sunburned?
A. infrared
C. ultraviolet light
B. microwave light
D. white light
6. He formulated the hypothesis that an electron being a particle has wave-like characteristics.
A. Albert Einstein
C. Louis de Broglie
B. Max Plank
D. Neils Bohr
7. Which property of light is responsible for white clouds, blue sky and red sunset?
A. Dispersion
C. Interference
B. Scattering
D. Diffraction
8. What natural occurrence is produced by the refraction of light as it travels between hot
and cold air?
A. mirage
C. virtual image
B. myriad
D. real image
9. Which of the following situations exemplifies the dispersion property of light?
A. The image of the flower in a mirror
B. The sparkling glow of the diamond ring
C. The swaying movement of coin underwater
D. The rainbow in the sky after the rain shower
10. Which of the following light phenomena is caused by diffraction of light?
A. Silver lining at the end of the clouds
B. Spectrum of colors on soap bubbles.
C. A secondary rainbow
D. Dark clouds
23
Iii
11. What effect does interference of light waves have on soap bubbles?
A. They become larger
B. They become heavier
C. They produced different colors at the surface.
D. They produced images of objects like a mirror.
12. After a rainstorm, a rainbow may appear in the sky. Which statement explains this
observation?
A. The raindrops act as prisms separating sunlight into a spectrum of colors.
B. The colors of the rainbow came from raindrops spread in the atmosphere
C. The white clouds are like prisms which are composed of different colors of
therainbow
D. When the incident light is reflected by the ground towards the clouds, it separates
them into different colors.
13. What light phenomena result in a spectrum of colors that escapes when two
reflectionshappened inside the water droplets?
A. A primary rainbow
C. A supernumerary bow
B. A secondary rainbow
D. A Halo
14. Who discovered the radio wave?
A. Heinrich Hertz
B. Heinrich Hess
C. Henry Hertz
D. Henry Hess
15. What was Hertz’s observation in his experiment?
I. When sparks flew across the main gap, sparks also flew across the secondary gap.
II. When sparks flew across the main gap, sparks stopped across the secondary gap.
III. When sparks flew across the main gap, the secondary gap does not ignite.
A. I only
C. II and III only
B. I, II and III
D. III only
iv
The Nature of Light
What I Need to Know
What is light? Is it matter or is it energy? Do you think it is a particle or a wave? For
hundreds of years, scientists disagreed on the nature of light. In this lesson, you will be able to
describe how the propagation of light, reflection, and refraction are explained by the wave model
and the particle model of light.
What’s New
Activity 3.1.1. Observing a Ball’s Path at Different Speeds (1 point each)
Find a space in your yard where you can safely play a ball. Face a wall, a boundary or
a fence at about two meters away from it. Throw the ball slowly. How will you describe the
trajectory path of the ball? Record your observation in the table 3.1A below. Throw this ball
again but this time do it very fast. Complete the table.
Table 3.1A Ball’s Speed Versus Path
Speed
Observation of Ball’s Path
Slow
Fast
What Is It
At low speeds, a curvature of a thrown ball was easily observed because of the
effect of gravity but at high speeds, the ball is inclined to follow a straight line. The second
observation on the ball is also true to the behavior of light. According to Sir Isaac Newton, light
travels in straight lines, thus its particles must move at very high speeds
Light can travel straight through empty space
(vacuum) until it hits something else. Once it
has hit another surface or particle, it is either
absorbed, reflected (bounces off), refracted
(direction and speed changes), scattered
(bounce-off in all directions) or transmitted
(passes straight through) as seen in figure
3.1A. But is light a wave or a particle?
Figure 3.1A: Propagation of Light
1
The nature of light can be explained by the following theories:
1. The Corpuscular (Particle) Theory – Newton’s Theory
According to the theory, Newton thought that light is made up of particles that travel
through space on a straight line. He explains further that:
 Reflection is the bouncing of light as it hits a surface. Newton demonstrated that particles
that collide with the surface bounce back (see figure 3.1Ba).
 Refraction is the bending of light. It is an attraction between the molecules of the medium
and the particles of light which contribute to the change of speed and direction as the particles
of the light travel inside the medium (see figure 3.1Bc).
(a)
(b)
(c)
(d)
Figure 3.1B. The reflection of light as (a) particles and (b) waves; refraction of light as (c) particles) and (d) waves
1. The Wave Theory of Light
Christian Huygens, a Dutch physicist, argued that if light were made of particles, then
when light beams crossed, the particles would collide and cancel each other. He proposed that
light was a wave similar to that of water waves.
Huygens’ Principle describes each point on a wave behaves as a point source for waves
in the direction of wave motion. Huygens’ wave model of light explains reflection, refraction, and
diffraction of light. According to him:
 Reflection happens when light bounces off an object. Upon hitting a smooth surface as
illustrated in figure b, the light would be reflected. The waves would bounce back in the
opposite direction following the Law of Reflection producing a reverse image of the wave (see
figure 3.1Bb).
 Refraction is the bending of waves when it enters a medium where its speed changes. In
figure d, the wavefront approaches the two media with different densities. Since the incident
wave is travelling at an angle, a small portion of the wavefront starts to slow down upon impact
to the boundary while the rest are maintaining their speeds. This condition makes the
wavefront bend while entering the second medium with a higher density (see figure 3.1Bd).
Light actually has a dual nature. It consists of a particle and travel as a wave. Its nature
as a particle, a wave or both may be used to explain but also depending on the phenomenon
(see table 3.1B).
Phenomenon
Reflection
Refraction
Interference*
Diffraction*
Polarization*
Photoelectric effect*
Table 3.1B Behavior of Light
Behavior of Light that can be explained by
Wave Theory
Particle Theory








*Shall be discussed in details in the succeeding lessons
2
What’s More
Activity 3.1.2 Exploring How Light Travels (10 points)
Go back to your front yard or backyard. Pick 3 best selfie spots. Before posing for your
camera, observe your shadow as you go through those spots.
1. Where did you see the shadows?
2. Did the shadows change?
3. Under what circumstances?
4. Take selfies facing different directions. In the context of light, under what circumstances did
you have a nice selfie photo? Justify your answer.
5. Upload your best and worst capture in your Physical Science group chat on Messenger or
Google Classroom.
What I Have Learned
Activity 3.1.3 Sharing My Insights (Criteria: Critical Thinking-5, Communication-5)
Based on the lesson on Corpuscles’ Theory and Wave Theory of Light, I have realized
that
What I Can Do
Activity 3.1.4 Reflecting Me (1 point each).
Complete table 3.1C to describe how reflection and refraction are explained by
the wave theory and the particle theory of light
Table 3.1 C Behavior of Light
Description of the Behavior of Light by
Phenomena
Wave Theory of Light
Reflection
Refraction
3
Particle Theory of Light
Energy of Light
What’s In
Light may behave as a particle, a wave or both depending on which light
phenomenon is observed. To scientists, colors of things are not substances of the things
themselves, but the frequencies of light emitted or reflected by things which are dependent on
their color pigments.
What I Need to Know
In this lesson, you will be able to explain how the photon concept and the fact that
the energy of a photon is directly proportional to its frequency can be used to explain why in
photographic darkrooms red light is used, why in ultraviolet light but not in visible light we get
easily sunburned, and how we see colors?
What’s New
Activity 3.2.1 Arranging Rainbow Colors (1 point each).
Open your Facebook app. Type visible light spectrum on the search bar. Go through
the resources and take note of the frequencies and energies of the different colors of light.
Using the colors below, complete the chart according to the increasing frequency and
increasing energy.
Parameter
Frequency
Energy
Red
Orange
1
2
Yellow
3
Green
Blue
4
5
Indigo
6
Violet
7
What happens to the energy of light as the frequency increases?
.
.
.
What Is It
The electromagnetic spectrum depicts all the types of light, including those that we
cannot see in our own eyes. In fact, most of the light in the universe is invisible to humans.
4
The light we can see, made up of the individual colors of the rainbow, represents only
a very small portion of the electromagnetic (EM) spectrum. It is called visible light as shown in
figure 3.2A. Other types of light include radio waves, microwaves, infrared radiation, ultraviolet
rays, X-rays and gamma rays — all of which are imperceptible to human eyes.
Figure 3.2A. The Electromagnetic (EM) Spectrum
The relationship between energy and frequency is given by the equation E = hf,
where h is 6.63 x10-24 joules-second called as Planck's constant. A direct relationship
exists; electromagnetic (EM) radiation is more energetic with a higher frequency.
Why do we get easily sunburned in ultraviolet light but not in visible light? The sun is
a source of the full spectrum of the ultraviolet radiation which is responsible for causing us
sunburn. This UV light has higher frequency than visible light, therefore it has higher energy.
Why is red light used in photographic darkrooms? Darkrooms used red lighting to allow
careful control light to pass through so that photographic paper which is light sensitive would
not become overexposed that will result in ruining the pictures during the developing process.
Red light in the visible region of the spectrum has the lowest frequency and lowest energy and
therefore it does not affect the photo developing process.
How do we see colors? Visible light is a small part within the spectrum that human
eyes are sensitive to and can detect. It is of different frequencies and each frequency is a
particular color. Objects appear in different colors because they absorb some colors and
reflect or transmit the others. Whatever color the object reflect or transmit is the color we see
in the object. White objects appear white because they reflect all colors. Black objects absorb
all of them so no light is reflected.
Other real-life applications of the Electromagnetic waves are specified in table 3.2A.
Table 3.2A EM Waves Applications
Type
Applications
Life sciences aspect
Issues
Radio
Communications remote controls
MRI
Requires controls
for band use
Microwaves
Communications, ovens, radar
Deep heating
Cell phone use
Infrared
Thermal imaging, heating
Absorbed by atmosphere
Greenhouse effect
Visible light
All pervasive
Photosynthesis, Human vision
Ultraviolet
Sterilization, Cancer control
Vitamin D production
Ozone depletion,
Cancer causing
X-rays
Medical Security
Medical diagnosis, Cancer
therapy
Cancer causing
Gamma rays
Nuclear medicine, Security
Medical diagnosis, Cancer
therapy
Cancer causing,
Radiation damage
5
What’s More
Activity 3.2.2 Matching Perfectly (1point each).
Directions: Match the expressions in column A with those in column B by placing the
letter that corresponds to the best answer on the space provided.
A
1. Using red light in photographic darkroom
B
a. higher frequency. higher energy
2. Getting sunburned in ultraviolet light
b. higher frequency. lower energy
3. Seeing white t-shirt as blue
c. lower frequency, higher energy
d. lower frequency, lower energy
What I Have Learned
Activity 3.2.3 Writing it Right (Criteria: Critical Thinking-5, Communication-5)
Based on the lesson on frequency and energy of light, I have realized that
What I Can Do
Activity 3.2.4 Spotting Similarities and Differences
(Criteria: Critical Thinking-5, Communication-5, Creativity-5)
Compare and contrast any two radio waves, microwave, infrared, visible light,
ultraviolet, x-ray and gamma ray in terms of energy, frequency and uses. Present your output
creatively.
6
Wave Property of an Electron
What I Need to Know
In this lesson, you should be able to cite some experimental evidence showing
that an electron can behave like a wave.
What’s In
In the preceding lesson, you learned that light can behave as a particle and as a
wave. The idea of photoelectric effects, which show the particle property of light fascinated the
French physicist Louis de Broglie. If light being a wave can show a particle-like property, then
electron and other particles may also have wave-like properties such as wavelength and
frequency.
What’s New
Activity 3.3.1 Let’s Match History!
1. Match the year, the scientist and their contribution to the development of the wave-like
property of the electron.
2. Write your answer in the column for Coded Answer.
Scientists
Contribution
1. 1900
Coded
Answer
1.
,
A. Albert Einstein
2. 1905
2.
,
G. proposed that electron could have
wave-like properties
H. Photoelectric effect
3. 1922
3.
,
4. 1924
4.
,
5. 1927
5.
B. Clinton
Davisson and Lester
Germer
C. Arthur Holy
I discovered Planck’s radiation law
Compton
J. announced the complementary
relation between the wave and
D. Max Planck
particle aspect of electron
E. Louis de Broglie K. Compton effect
6. 1928
6.
A (Year)
,
,
L. experimentally established the
wave-nature of electron
F. Neils Bohr
7
What Is It
In 1900, Max Planck was able to formulate and discover the so-called Plank’s
constant which he included in his discovery of Plank’s radiation law. In 1905 German physicist
Albert Einstein first showed that light, being considered as a form of EM wave, can be thought
of as a particle and localized in packets of discrete energy. This was shown in his photoelectric
effect experiment. The observations of the Compton effect in 1922 by American physicist
Arthur Holly Compton could be explained only if the light had a wave-particle duality.Fascinated
with the idea that light as a wave can have a particle-like property, in 1924, French physicist
Louis de Broglie proposed that electrons and other discrete bits of matter, which until then had
been conceived only as material particles, must also have wave properties suchas wavelength
and frequency. Later in 1927, the wave nature of electrons was experimentallyestablished by
American physicists Clinton Davisson and Lester Germer on their Davisson- Germer
experiment. An understanding of the complementary relationship between the wave aspects
and the particle aspects of the same phenomenon was announced by Danish physicist Niels
Bohr in 1928.
What’s More
Activity 3.3.2 Where Can I Find You?
1. Encircle as many words that
relate to the wave-like property
of electron on the puzzle mat.
2. It can be horizontal, vertical,
or diagonal.
3. Write the words that you found
in the puzzle in your journal
notebook
4.
Good luck and enjoy the
puzzle.
What Is It
Electron being considered as a wave created questions that gain the interest of other
fellow scientists. Among the questions that lingered on the minds of other scientists was that
“if electron traveled as a wave, then where could be the precise position of the electron within
the wave?”
The answer to this question was given by German physicist Werner Heisenberg in
1927, in his famous Heisenberg Uncertainty Principle. He articulated that both the momentum
and position of the electron cannot be measured exactly at the same time.
8
Another scientist in the name of Erwin Shrodinger derived a set of equations also
called wave functions for electrons as a result of de Broglie’s hypothesis and Heisenberg’s
uncertainty principle. He formulated the equations that would specify that the electrons
confined in their orbits would set up standing waves and the probability of finding the electrons
in the orbitals could be described as the electron density clouds. The greatest probability of
finding an electron in an orbital is in the densest area, likewise, the lowest probability of finding
an electron is in the orbital of least dense.
What I Have Learned
Activity 3.3.4 Let me Test Myself!
What is some experimental evidence showing that an electron has a wavelike
property? Write your answer in your journal notebook.
What I Can Do
Activity 3.3.5. Challenge the Scientist in Me!
I.
Choose any 1 of the activity.
A. Search on Davisson-Germer Experiment that confirms De Broglie’s hypothesis.
Make a synthesis of their experiment. Write it in your journal notebook.
B. Watch the video on Youtube “De Broglie wavelength/Khan Academy @
https://www.khanacademy.org/science/physics/quantum-physics/toms-andelectrons/v/de-broglie-wavelength. Write a synthesis of the video on your journal
notebook
9
Properties of Light
What’s In
As you may recall, the wave-particle nature of light can explain why light is
reflected or it may bounce back as it hits an opaque surface and it shall be refracted or bend
as it passes through a transparent material. In this lesson, you shall encounter more properties
of light that may uncover the formation of rainbows, the rainbow-colored soap bubbles that
you played with your younger siblings, the beautiful horizon that you experience in the late
afternoon and white fluffy clouds below the blue sky during the midday.
What’s New
Do you ever wonder how multicolored rainbows are formed? Perform the next
activity diligently to know-how.
Activity 3.4.1A Am I Dispersed? (Adopted from project EASE-physics Module 3)
Materials:
a prism or a clear bottle half-filled with water
Flashlight or sunlight
White bond paper/white wall
Procedure:
Hold a prism or a bottle half-filled with water against the sunlight or any
lightsource like a flashlight. Observe its reflection in a white bond paper or white wall.
Guide questions:
1. What do you see in the white bond paper/white wall?
2. Enumerate the colors you observe.
Activity 3.4.1B What a Colorful Day
Now, get your pen and journal notebook and go outside for a while and look up the
sky above you. Note down the things and colors you have noticed. Repeat your observation
at any time of the day and in the late afternoon. You may do this observation activity for a
series of 2-3 days when the weather Is fine. Keep your journal notebook handy. Good luck
What Is It
Dispersion & Scattering of Light
As light enters into a prism or an object that may
act as a prism, it separates into different band of colors.
This separation of white light into different colors as it
passes through a prism is called dispersion. The
separated band of colors, red, orange, yellow, green,
blue, indigo and violet, range from 400 nanometers to
700 nanometers
10
Figure 4.1 Dispersion of light in a Prism
in wavelength. Dispersion occurs due to the slight
difference in the refractive index of each color.
A rainbow is formed after a rain shower when
droplets of water in the sky act as a prism that separates
the rays of the sun hitting the water droplets into a band
of different colors.
Figure 4.2. A rainbow captured after a
rainshower in Bayabas, Cagayan de Oro
City. Photo credits to Ms. Maria Chicany
R. Blegario
Scattering of light is responsible for this bluecolored sky and beautiful horizon. Tiny dust particles,
and atoms of oxygen and nitrogen in the atmosphere
which are far apart from each other act as the
scatterer. They scatter sunlight in all directions. Of the
band of colors of light, violet has the shortest
wavelength of 400 nanometers. It is scattered the most,
followed by indigo, blue, green, yellow, orange and red
which is scattered the least. But our eyes are not
sensitive to indigo and violet, and blue is most
predominant to our site , so we see the blue sky.
Figure 4.4. A view from the Beach of Maniso, Balingasag, Misamis Oriental.
Photo credits to Ms. SJ Khu.
Figure 4.3.A view from the 2nd flr new JHS
building of Bayabas NHS, Cagayan de Oro
City. Photo credits to JJ Ragandang
In the late afternoon where the sun is on the horizon,
the longer wavelength red light reaches our eyes
more than the blue light which is scattered the most.
Red being scattered the least is transmitted and
passed through more of the atmosphere than any
other color. Thus, it is the red color together with
some orange that reaches our eyes in the late
afternoon and we see the beautiful red-orange
sunset.
Clouds are made of water droplets of varying
sizes. Smaller droplets scatter blue, medium droplets
scatter green and yellow and larger droplets scatter red
color. A combination of these color results in white
clouds.
Figure 4.5.A view from San Franz, El Salvador City
Photo credits to Mr. Zigger Villahermosa, SH of
San Franz ES, El Salvador City Division
Figure 4.6. Dark clouds in the sky over the newJHS building of
Bayabas NHS, CDO
Photo credits Ms, JJ Ragandang
11
Rain clouds appear dark because
the water droplets become bigger and
denser and it can absorb more light
than scatter it. Almost all colors are
absorbed and the resulting color is
dark or even black.
So, the next time you look up the
sky and view the horizon, you know
the science behind its beauty.
12
What’s More
Activity 3.4.2A Let Me Interfere!
Materials: 10 mL Liquid soap, 500 mL water, basin
Procedure: Put some 500 mL water in a basin and pour 10 mL of liquid soap. Stir and make
soap bubbles. Blow on soap bubbles. Observe.
Guide Question:
What can you observe in the soap bubbles? Write your observation on your journal
notebook.
Activity 3.4.2B Let me see you through!
1. Look at the light from a source such as a fluorescent bulb through the slit between your
fingers. What do you observe? Do you see vertical white and dark bands? What
causes these bands?
2. Repeat step 1 but make the slit narrower. Compare your observations with the previous
one.
3. Write your observations in your journal notebook.
What Is It
Interference & Diffraction of Light
The beautiful spectrum of colors reflected on the soap bubbles are produced by the
interference of light. It occurs when 2 waves meet while traveling on the same medium. It
may be constructive interference producing bright fringes or destructive interference producing
dark bands. In the case of soap bubbles, the incident rays of white light constructively interfere
in the different regions of the bubbles producing the rainbow-colored appearance.
Iridescence is the term used to refer to the production of colors by interference in thin
films. Other examples may include the beautiful band of colors you see in a. shiny compact
disk, water with some oil spill, the colorful feathers of birds, the fan-like feathers on a peacock,
the beautiful changing colors on the scales of a snake and the colors on an oyster shell. The
interference of light clearly demonstrates the wave nature of light. See the sample photos
below.
Figure 4.7. Some real-life examples of Interference of Light
13
As you look at the light through the slit between your fingers, you will observe the
vertical white and dark bands which is due to the bending of light as it passes through an
opening or an obstacle. This is described as a diffraction of light. Diffraction is dependent on
the size of the obstacles, that is, it will take place if the size of the obstacle is comparable to
the size of the wavelength of light which is from 400 nanometers to 700 nanometers. If the
size of the slit is near to this limit, only then we can observe the phenomenon of diffraction.
That is why the narrower the slit, the more pronounced the pattern becomes. See the sample
photos below.
Figure 4.8. Some observable examples of diffraction of light
What I Have Learned
Activity 3.4.3 You Complete Me!
I. Complete the table below: Write your answer in your journal notebook.
Properties of Light
1.
Description
Applicable light phenomena
2.
Rainbow
Scattering of light
3.
4.
Diffraction
5.
6.
7.
8.
Rainbow-colored
appearance in soap bubbles
What I Can Do
Activity 3.4.4 Let Me be a Collector!
Take and collect pictures applying at least two of the four properties of light
mentioned in this lesson. Post it on your journal notebook and briefly describe the science
behind the pictures. Submit your journal notebook to your teacher for the rating.
14
Various Light Phenomena
What’s In
In lesson 4, you have learned that rainbows are formed due to the dispersion of light
in water droplets that acts as a prism. You have also learned that the blue sky, the reddish
sunset and the white and dark clouds are products of the scattering of light in the atmosphere;
the rainbow-colored soap bubbles are due to the interference of light and the bright fringes
and dark bands in shadows are results of the diffraction of light.
In the previous lesson, you knew that light reflects or bounces back as it hits an opaque
object such as a mirror and transmits through transparent objects such as glass and lenses.
Light refracts or bends as it enters from one medium to another with different optical density.
You also knew that the colors we see on the object are the color of light that is reflected by the
object to our eyes. The green color of the leaves is due to the green light that is reflected by
the leaves to our eyes, and as the leaves absorbed all other colors only green is reflected.
These behaviors of light produce spectacular light phenomena that we often see in our
daily life and sometimes we may not notice it.
What I Need to Know
In this lesson, you are expected to explain various light phenomena such as your
reflection on the concave and convex side of a spoon, mirage, haloes, sundogs, primary and
secondary rainbows and supernumerary bows, You are also expected to explain why a red
laser light passes through easily on red cellophane than on a green one and why colors of
clothing appear different in artificial light as compared to natural sunlight.
What’s New
Activity 3.5.1A. My Spoony Image
1. In a well-lighted room, hold a shiny spoon at armlength with the backside
facing at you. Look at your image and describe your observation.
2. Now, turn the spoon and hold it at armlength such that the front side faces
you. Observe and describe your image.
3. Write your observations in your journal notebook.
Activity 3.5.1B. May I Pass Through
1. Point a red laser light at 900 or perpendicular to red colored cellophane. Observe the
transmitted light on a screen (maybe a white bond paper or white wall). Write your
observation in your journal notebook. Note: If red laser light is not available, you may
use a red bulb.
2. This time, use green cellophane instead of red and do the same as procedure no. 1.
What do you observe? Again, write your observation in your journal notebook.
15
What Is It
For activity 3.5.1A, the backside of the spoon represents the convex mirror while the
front side of the spoon represents the concave mirror. Recalling the images formed in a convex
and concave mirror. In a convex mirror, reflected light rays diverge as if it originates from the
imaginary focus of the mirror, thus producing a small, upright and laterally reverse image just
as what you observe. The image is upright because the point of intersection of the extended
reflected light rays through which the image is formed is above the principal axis. See figure
5.1 below.
For a concave mirror, incident light rays parallel to the principal axis bend towards
the focus of the mirror as it reflects, thus producing a small, laterally reversed and upside down
or inverted image. The image is inverted because the point of intersection of the real reflected
light rays is below the principal axis.
For Activity 3.5.1B, colored cellophane acts as filters for allowing certain colors to pass
through while absorbing the other colors. In the case of the activity, red laser light passes
through more easily in red cellophane than in green one because much of the red light is
absorbed in the green cellophane.
Light is transmitted in transparent materials without being scattered at an angle of 90
degrees, otherwise, light is refracted, but not 100 % of the incident light is transmitted, some
are absorbed and others are reflected.
When light hits an object, some of its frequencies are absorbed and some are reflected.
Such in the case of green leaves, only green frequency is reflected while the other frequencies
are absorbed by the object. The green light is reflected in our eyes, and we see it green. When
all frequencies of light are reflected, we see a white object, such as the white clouds, but when
all frequencies of light are absorbed, we see the object black.
Colored objects have pigments capable of reflecting specific colors of light. A blue
colored dress reflects the blue frequency and absorbs the other. But comparing the results of
reflection from natural sunlight and an artificial light source such as from a LED light, the color
intensities are different. The blue dress would appear pale blue in an artificial light because it
contains less amount of blue light as compared to the natural sunlight.
16
What’s More
Activity 3.5.2. Picture Analysis
Analyze the photographs of different optical phenomena and answer the guide
questions below in your journal notebook.
Guide Questions:
1. On a very sunny day, have you observed the apparent pool of water on a straight
highway? What do you call this phenomenon and what causes this? Which photo is
this?
2. Which photo shows a halo? What causes the formation of haloes?
3. Which photo depicts sundogs? What property of light causes sundogs?
4. Rainbows are a spectacular view in the sky. What is the difference between a primary
rainbow and a secondary rainbow?
5. Which among the pictures is a supernumerary bow? What property of light causes its
formation?
What Is It
Various Light Phenomena
The pictures above are some of the many examples of light phenomena that are
governed by the properties and behavior of light such as reflection, refraction, dispersion,
scattering, interference and diffraction.
Mirage is a natural occurrence produced by the refraction of light as it travels between
hot and cold air. It is mostly observed on a straight highway at noontime when the sun heats
up the road to high temperature. It is an illusion of water on the highway on a very hot sunny
day.
Haloes and sundogs are optical phenomena that happen when light is reflected or
refracted by ice crystals in the atmosphere. Haloes are formed around the sun or the moon
when ice crystals refract light twice, making 220 refraction from its original direction.
17
The refraction occurs in hexagonal ice crystals mostly found in the cirrus clouds.
Sundogs have the same mechanism as the formation of haloes, however, they are most
visible when the sun is near the horizon. As light enters the face side of the hexagonal ice
crystals, light exits at 220 on the other side towards the eyes. Mock sun or parhelion are the
other terms for sundogs.
In lesson 4, you know that rainbows are
formed from the dispersion of light on droplets of
water in the atmosphere. When water droplets
refract light between 40° to 42°angle towards the
eyes, a primary rainbow is formed. We may see
a second rainbow which is fainter than the first.
This happens when two reflections are made
inside the water droplets. Secondary rainbow is
formed when water droplets refract the light at an
angle between 54° and 52° making the colors in
reverse order. Supernumerary bows are found in
the inner part of the primary rainbow due to the
inference of the wave crest. They are usually
greenish–purple colors.
Did you know that a rainbow always appears opposite the sun? So, the next time
you want to see a rainbow after the rainshower, let your back face the sun and let your eyes
wander in the lower sky.
What I Have Learned
Activity 3.5.3 Let’s Test your Understanding
Answer the questions briefly. Write your answers on your journal notebook.
1. Compare and contrast the images form on the front side and in the backside of a
shinyspoon. What does the front side of the spoon represent? The backside?
2. Why does red light passes through easily in red cellophane? What happens to the
green light as it passes through the red cellophane?
3. The color of the dress when artificial light is shone upon it is different compared to
thecolor of the dress when natural sunlight is shone upon it. Why?
4. What behavior of light is responsible for the formation of mirage?
5. What are the similarities and differences between a halo and a sundog?
6. How is a primary and secondary rainbow different?
7. What is a supernumerary bow? How is it form?
What I Can Do
Activity 3.5.4 Let’s Illustrate!
Now that you have studied various light phenomena, select at least 3 and make
a sketch or illustrate the following in your journal notebook. Color your illustrations properly.
1.
2.
3.
4.
5.
A primary and secondary rainbow from an observer’s eye
A supernumerary bow located at the inner of a primary bow.
An image of a red rose reflected on the front side of the spoon.
An image of a native fruit as reflected on the backside of the spoon.
The color difference of an orange dress when an artificial light shines on it side
byside with the same dress illuminated by the natural sunlight.
18
HERTZ’S RADIO PULSES
What’s In
In the previous topic, you have learned about light phenomena that are any
observable events that resulted from the interaction of light and matter. Various light
phenomena are formed due to the interaction of light from the sun or moon with the
atmosphere, clouds, dust, water, and other particulates. Light phenomena include rainbows,
haloes, the color of clouds and the sky.
What I Need to Know
(http://www.brainkart.com/article/Production-and-properties-of-electromagnetic-waves---Hertz-experiment_38544/)
o Who is Heinrich Rudolf Hertz? What was his contribution to electromagnetic waves?
o Why did Hertz able to do this kind of experiment?
o How did Hertz experiment produced radio pulses?
o Why is the unit of frequency Hertz?
o What is the importance of Hertz’s contribution nowadays?
The questions above will give you an idea of the things Hertz did and how it became
an important part of the new generation. Before you proceed please try to answer the
questions above using prior knowledge on this topic.
What’s New
Activity 3.6.1. Find Me Clearly
Turn On an AM/FM Radio. First, select clear AM radio stations. Record the names
and frequencies of the radio stations with clear reception. This time tune in to FM radio
stations. Record again the names and frequencies of stations that give clear reception. What
have you observed on the radio frequency when you turn the dial knob to the right and to the
left? Is there a difference in the frequency of AM and FM radio stations? Do you know how
radio signals are transmitted and who discovered it? Write your answers in your journal
notebook.
19
What Is It
“I do not think that the wireless waves I have discovered
will have any practical application.”
HEINRICH HERTZ
1890
https://www.famousscientists.orghow-hertz-discovered-radio-waves
Heinrich Rudolf Hertz (1857–1894) was a
German physicist who became the first person to transmit
and receive controlled radio waves. He was the first to
conclusively prove the existence of electromagnetic
waves theorized by James Clerk Maxwell's
electromagnetic theory of light.
Hertz proved the theory on how to transmit and
receive radio pulses using experimental procedures. He
planned a set of experiments to test Maxwell's
hypothesis. This apparatus consists of polished brass
knobs, each connected to an induction coil and separated
by a tiny gap over which sparks could leap as shown in
Figure 3.6.1
Figure 3.6.1
What’s More
Activity 3.6 2. Hertz’s Experiment
Make an improvise Hertz’s experiment. Using the picture below as your guide or
you can watch the you-tube https://www.youtube.com/watch?v=9gDFll6 Ge7g. Picture your
output
and
paste
it
into
your
journal
notebook.
(https://www.youtube.com/watch?v=A5mXwBABgDs)
20
What I Have Learned
Activity 3.6.3. Test your Memory
Answer the following questions briefly: Write your answers in your journal notebook.
1. What is the unit of frequency? In whose honor is it named?
2. Why will a large voltage be used to produce sparks based on Hertz experiment?
3. How did Hertz produce sparks?
4. Was Hertz successful in proving James Clerk Maxwell's electromagnetic theory of
light?
What I Can Do
Activity 3.6.4. Research Time
Do some research work on the given topic below and record your answer in
your journal notebook.
1. Differences between AM and FM.
2. Why NTC order to stop the ABS-CBN from using their frequency?
Summary
1. The speed of light is finite and it can travel through empty space in straight lines.
2. In a given phenomenon, light behaves as a wave, a particle or both.
3. The energy of light is directly proportional to its frequency. The higher the frequency the
higher is the energy.
4. Electrons being a particle has also wave-like properties.
5. The various light phenomena are governed by the behavior and properties of light such
as photoelectric effect, reflection, refraction, dispersion, scattering, interference and
diffraction of light.
6. Mirage, rainbows, supernumerary bows, haloes, sundogs, red sunset, blue sky and
white clouds are some of the spectacular light phenomena we can observe in our life.
7. Heinrich Rudolf Hertz discovered radio pulses and the unit of frequency, Hertz, is
named after him.
21
Assessment (Post Test)
Multiple Choice. Select the letter of the best answer from among the given choices.
1. In reflection, how is the wave theory of light related to particle theory of light?
A. They complement each other
B. They are contradicting each other
C. There is no difference between the wave theory and particle theory of light.
D. Together, they show that reflection is popular than refraction.
2. Which of the following best describes the refraction phenomenon?
A, It is explained better using the wave model of light than the particle model of light.
B. It is explained using the photon theory of light.
C. The particle model predicts that particles of light will speed up as they pass through
the boundary between air and water.
D. The wave model correctly predicts that light will slow down as it passes through the
boundary between air and water
3. How do we see a tree?
A. The light that reaches our eyes has been reflected by the tree.
B. The light that reaches our eyes has been refracted by the tree
C. The light that reaches our eyes has been separated into a spectrum by the tree.
. D. The light that reaches our eyes has undergone interference in passing through
the tree
4. In photographic darkrooms, what is the reason why red light is used?
A. Most of the photographic films are not sensitive to red light
B. Photographic paper is not sensitive to white light
C. The frequency for red light is low hence the energy of the photos is less
D. The frequency of the red light is high hence the energy of the photos is high.
5. E=hf is an equation that describes the relationship between the energy (E) and frequency of
light (f). Why do we easily get sunburned in ultraviolet light but not in visible light?
A. Ultraviolet light is of higher frequency than visible light; therefore, it has higher
energy and is sufficiently energetic to cause skin damage,
B. Ultraviolet light has longer wavelengths than visible light; therefore, it has lower
energy and is sufficiently energetic to cause skin damage
C. Ultraviolet light has shorter wavelengths than visible light; therefore, it has higher
energy and is sufficiently energetic to cause skin damage
D. Ultraviolet light is of lower frequency than visible light; therefore, it has lower
energy and is sufficiently energetic to cause skin damage
6. He formulated the hypothesis that an electron being a particle has wave-like characteristics.
A. Albert Einstein
C. Louis de Broglie
B. Max Plank
D. Neils Bohr
7. Which property of light is responsible for the silver lining at the edges of the clouds?
A. Dispersion
C. Interference
B. Scattering
D. Diffraction
8. It is a natural occurrence produced by the refraction of light as it travels between hot and
cold air.
A. mirage
C. virtual image
B. myriad
D. real image
22
9. Which of the following situations exemplifies the dispersion property of light?
A. The image of the flower in a mirror
B. The sparkling glow of the diamond ring
C. The swaying movement of coin underwater
D. The rainbow in the sky after the rain shower
10. Explain when can diffraction of light occurs?
A. When photons oscillate in certain directions are absorbed, while others
thatoscillate in line with the filter pass through.
B. when light strikes the boundary between substances at an angle greater than
thecritical angle.
C. when waves spread and bend as they pass through small openings or
aroundbarriers.
D. when two or more waves overlap or intersect.
11. What effect does interference of light waves have on soap bubbles?
A. They become larger
B. They become heavier
C. They produced different colors at the surface.
D. They produced images of objects like a mirror.
12. After a rainstorm, a rainbow may appear in the sky. Which statement explains
this observation?
A. The colors of the rainbow come from raindrops spread in the atmosphere
B. The raindrops act as prisms separating sunlight into spectrum of colors.
C. The white clouds are like prisms which are composed of different colors of
therainbow
D. When the incident light is reflected by the ground towards the clouds, it
separatesthem into different colors.
13. What light phenomena results in a spectrum of colors that escapes when two
reflectionshappened inside the water droplets?
A. A primary rainbow
C. A supernumerary bow
B. A secondary rainbow
D. A Halo
14. The reason why Hertz used the same length of wire from CA to CB.
I. The voltage reached at the same direction.
II. The voltage reached at the same point.
III. The voltage reached at the same time.
A. I only
C. II and III only
B. I and II only
D. III only
15. Hertz’s observation on his experiment.
I.
When sparks flew across the main gap, sparks flew across the secondary gap.
II.
When sparks flew across the main gap, sparks stopped across the secondary gap.
III.
When sparks flew across the main gap, secondary gap do not ignite.
A. I only
C. II and III only
B. I, II and III
D. III only
23
nioighigSh S
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Physical Science
Quarter 2 - Module 4
Einstein’s Theory of Relativity
24
Table of Contents
What This Module is About ............................................................................... i
What I Need to Know ........................................................................................ i
How to Learn from this Module ......................................................................... ii
Icons of this Module .......................................................................................... ii
What I Know..................................................................................................... iii
Lesson 1:
Special Relativity and the Consequences of its Postulates .........1
What I Need to Know .................................................................................................... 1
What’s New: Observing Light .................................................................................................... 2
What Is It ...................................................................................................................... 2
What I Have Learned: Test Your Analysis ..................................................................... 3
What I Need to Know .................................................................................................... 4
What’s New: Guessing time ...................................................................................................... 5
What Is It ...................................................................................................................... 5
What I Have Learned: Explain Briefly ............................................................................ 8
Lesson 2:
The Consequences of the Postulates of General Relativity .........9
What’s In ....................................................................................................................................... 9
What I Need to Know .................................................................................................... 9
What’s New: Find a Partner and The Fabric of Curvature ................................................. 10
What is It ..................................................................................................................... 13
What’s More: I am Bent............................................................................................................ 13
What I Have Learned: Expound Me ............................................................................ 13
Lesson 3:
Speeds and Distances of Far-off Objects .................................... 14
What I Need to Know ..................................................................................................... 14
What’s New: Knowing Parallax ................................................................................................... 15
What Is It ........................................................................................................................ 15
What’s More: Show It to Me! ....................................................................................................... 22
What I Have Learned: Test Your Analysis ...................................................................... 22
What I Can Do: Make Me Complicated: Parallax ............................................................ 22
Lesson 4:
The Expanding Universe ............................................................... 24
What’s In ......................................................................................................................................... 24
What I Need to Know ..................................................................................................... 25
What is It ........................................................................................................................ 26
What’s More: The Expanding Universal Galaxies ...................................................................26
What I Have Learned: Calculating the Age of the Universe ............................................ 32
What I Can Do: Sketch Me Up!....................................................................................... 32
25
Summary........................................................................................................ 33
Assessment: (Posttest) .................................................................................. 35
Key to Answers .............................................................................................. 37
References..................................................................................................... 40
26
What This Module is About
This Module in Physical Science attempts to briefly introduce you to the main ideas
and consequences of Albert Einstein’s postulates for his Special and General Theories
of Relativity. These theories are innovative examples of the unlimited result of a persistent
and creative process that Einstein started as a thought experiment during his inquisitive years
at age 16. He pursued this thought experiment on ‘chasing a beam of light’ for close to 10
years until his early adulthood when he came up first with his Theory of Special Relativity.
The introductory notes for each lesson provide a brief background of the activity, while
the activity guide questions and analogies will help you understand both the conceptual and
mathematical ideas of Einstein’s Special and General Theories of Relativity. The activities
are designed to build your interest in understanding the applications of relativity to medical
technology, nuclear power, Global Positioning Systems, and space explorations designed to
probe our expanding universe.
The following are the 3 weekly lessons contained in this module:
1. Special Relativity and The Consequences of the Postulates of Special Relativity,
2. Consequences of the Postulates of General Relativity, and
3. Speeds and Distances of Far-off Objects and The Expanding Universe
What I Need to Know
At the end of this module, you should be able to:
1. Explain how special relativity resolved the conflict between Newtonian Mechanics and
Maxwell’s Electromagnetic Theory (S11/12PS-IVi-j-69),
2. Explain the consequences of the postulates of Special Relativity (e.g., relativity of
simultaneity, time dilation, length contraction, mass-energy equivalence, and cosmic
speed limit) (S11/12PS-IVi-j-70),
3. Explain the consequences of the postulates of General Relativity (e.g., correct predictions
of shifts in the orbit of Mercury, gravitational bending of light, and black holes) (S11/12PSIVi-j-71),
4. Explain how the speeds and distances of far-off objects are estimated (e.g., doppler effect
and cosmic distance ladder) (S11/12PS-IVj-72), and
5. Explain how we know that we live in an expanding universe, which used to be hot and is
approximately 14billion years old (S11/12PS-IVj-73).
How to Learn from this Module
To achieve the objectives cited above, you are to do the following:
• Take your time to read the lessons carefully.
• Follow diligently the instructions in the activities and exercises.
• Answer all the given tests and exercises.
i
27
Icons of this Module
What I Need
to Know
This part contains the learning objectives that are set
for you to learn as you go along the module.
What I know
This is an assessment as to your level of knowledge
in the subject matter at hand, meant specifically to
gauge prior related knowledge.
What’s In
This part connects the previous lesson with the
current one.
What’s New
An introduction of the new lesson through various
activities before it will be presented to you.
What is It
These are discussions of the activities designed to
deepen your discovery and understanding of the
concept.
What’s More
These are follow-up activities that are intended for
you to practice for you to master the competencies.
What I Have
Learned
Activities designed to process what you have learned
from the lesson.
What I can
do
These are tasks designed to showcase your gained
skills and knowledge as applied to real-life concerns
and situations.
Assessment
This is an end-of-module assessment as to your level
of mastery in achieving the learning objectives for the
subject matter at hand.
Additional
Activities
These are additional activities that are intended to
strengthen your gained skills, knowledge, attitudes,
and values.
ii
What I Know (Pretest)
Multiple Choice. Select the letter of the best answer from among the given choices.
1.
At what rate do the EM waves travel according to Maxwell's electromagnetic wave theory?
A. 3.00 x 108 ms-1
B. 6.00 x 108 ms-1
C. 3.00 x 10-8 ms-1
D. 6.00 x 10-8 ms-1
2. Which among the following resolves the conflict between Newtonian mechanics and
Maxwell's electromagnetic theory?
A. Theory of general relativity
C. Law of universal gravitation
B. Theory of special relativity
D. Law of conservation of energy
3. Einstein's theory of special relativity modified the classical laws of motion by
to account for relativistic transformations in objects that move close to the
speed of light.
A. Herts
C. Maxwell
B. Galileo
D. Newton
4. Which of the following are the postulates of special relativity?
I. The color of light is the same for all frames of reference.
II. The speed of light is the same for all frames of reference.
III. The relative speed of objects is the same for all observers in moving
frames of
reference.
IV. The laws of physics are the same for all observers in uniformly moving
frames
of reference.
A. I and II
C. II and III
B. I and III
D. II and IV
5. Einstein's famous equation E = mc2 implies that mass is
.
A. always greater than energy
C. can be converted to energy.
B. always smaller than energy
D. can be converted to a speed of light
6. Simultaneity is
A. dilated
B. invariant
.
C. absolute
D. relative
7. One of two identical twins is an astronaut, while the other is a real estate broker. The
astronaut embarks on high-speed space travel and is gone for several years. Upon the
astronaut's return, the two twins reunite and observed their physical appearances. The
observation will be that
.
A. both have aged the same
C. the astronaut has aged more
B. the astronaut has aged less
D the real estate broker has aged less
8. When compared to an identical clock in a moving reference frame, a clock in a stationary
reference frame will appear to run
.
A. at the same rate
C. faster
B. backward in time
D. slower
iii
9. An observer from afar, tracks a blue object moving towards a black hole. As the object
nears the black hole, the observer notes the color of the blue object as
.
A. black
C. green
B. blue
D. red
10. The Principle of Equivalence in the General Theory of Relativity states that inertia and
gravitational masses are
.
A. identical
C.not significant
B. increasing
D.varied
11. Which of the following is not a consequence of the General Theory of Relativity?
A. Black Hole
C. Precession in the Orbit of Mercury
B. Gravitational Lensing Effect
D. Time Dilation
12. The Einstein Cross is an evidence of
A. Black Hole
B. Gravitational Lensing Effect
.
C. Increased gravity
D. Shifting of orbit
13. A galaxy cluster in Ursa Major has a recessional velocity of 15, 000 km/s. Using the best
estimate for Hubble’s constant, find the distance to the galaxy cluster.
A. 221 Mpc
C. 121 Mpc
B. 211 Mpc
D. 112 Mpc
14. What happened to the brightness of the candle when the square of its distance
decreases?
A. increases
C. Remains the same
B. decreases
D. Zero
15. What do you call the age-old technique used by astronomers to determine more distant
objects?
A. Parallax
C. The standard candle
B. Cepheid variable stars
D. Doppler Effect
16. Who discovered that Cepheid variable stars could be used to accurately measure
distances?
A. Alan Guth
C. Albert Einstein
B. Edwin Hubble
D. Henrietta Leavitt
iv
Lesson
1
SPECIAL RELATIVITY AND THE
CONSEQUENCES OF ITS
POSTULATES
What I Need to Know
Before Einstein’s theories of relativity, the idea of relativity prominently started
with Galileo who explained that all events of motion are observed or measured with respect
to an observer’s point of reference. Wherever you happen to be right now, it seems like you
are at a fixed point, and that things move relative to you. All you do is to select a fixed
coordinate for space and time commonly called a frame of reference. You then simply add
or subtract any relative velocity because the laws of motion do not change in a uniform or an
inertial frame of reference. Recall that the concept of ‘inertia’ was first hinted at by Galileo,
the term was first used by Kepler, and finally the definition was first given and used by
Newton.
In 1687, Newtonian Mechanics, also called classical mechanics, combined into one
the theory of Kepler’s planetary laws of motion, Galileo’s law of relativity for uniform motion,
Descartes’ law of conservation of momentum, and Huygen’s analysis of circular motion. In this
theory, the motion of both heavenly and terrestrial objects is built on one force law and three
independent basic concepts of:
(a) the absolute time that is the same for all observers on earth as well as for those
in orbit that imply simultaneous events independent of location and state of motion,
(b) absolute three-dimensional space where any object can freely move, and the
inertial mass of objects that resist acceleration.
From Newtonian mechanics, all inertial frames, physical laws, and universal
constants that arise in it are the same.
On the other hand, Maxwell’s Electromagnetic Theory in 1856 integrated into four
mathematical equations the extensive research of Faraday and others that led to the fact
that electrical and magnetic fields propagate as electromagnetic waves at the same
constant speed with which light travels in a vacuum. Thirty years later (when Einstein was
7 years old), Hertz first demonstrated the production and transmission of one of the
electromagnetic waves when he experimentally produced radio pulses.
Another 9 years later, Einstein at 16, amused himself with a thought experiment of him
‘chasing a beam of light while riding another beam’. But the manner of adding light velocities
according to Newtonian mechanics, obviously contradicting the constancy of the speed of
light according to the Electromagnetic Theory, has occupied Einstein’s mind during his spare
time well into his mid-twenties.
How then did Einstein’s teenage pursuit and eventual publication of the Theory of
Special Relativity resolve the conflict between two fundamental theories governing Newtonian
Mechanics and Electromagnetic Waves? What are the central ideas, postulates,
1
and consequences that underly Einstein’s Theory of Special Relativity? Hop on, as you chase
to understand this important topic!
What’s New
Activity 4.1.1 Observing Light
1. Examine Figure 4.1.1. Recall Newton’s theory on motion and Maxwell’s theory on the
speed of light. Why did the light reach both presidents at the same time? Which theory
can correct and explain this observation? Write your answer in the journal notebook
Figure 4.1.1 Two stationary observers
equidistant from a stationary source of light
Source: https://doi.org/10.1119/1.4895355
Figure 4.1.2 Light moves along a moving
reference frame past a stationary observer.
Source: https://aether.lbl.gov/www/classes
/p139/exp/rel2.gif
2. Study Figure 4.1.2 and analyze the given situation to answer the questions that follow.
Write your answer in the journal notebook.
Mrs. Yap is stationary along a roadside watching Mr. Yap standing still on a truck which is
moving leftwards with velocity v. She saw Mr. Yap switched on a flashlight in the direction in
which he is moving.
Question: Applying Einstein’s postulate of special relativity, what was Mrs. Yap’s observation
about the light as it travels? What about Mr. Yap’s observation? Do they have the same
observation?
Hi! I am Mrs. Brighty, I will share to
you everything you need to know
about the Special Theory of Relativity.
What Is It
In the first scenario of Activity 4.1.1, Maxwell’s theory can account for why the light reaches both
presidents at the same time. Recall that Maxwell’s electromagnetic theory consists of four
formulas from the different works of Faraday and other physicists that unite all the concepts of
electricity and magnetism that describes that a time-varying magnetic field acts as a source of
electric field and that a time-varying electric field acts as a source of a magnetic field. Each
sustaining the other, forming the electromagnetic wave spectrum, of which light is a part of. In
1886, Hertz demonstrated that these waves really exist with his demonstration of
the Hertzian waves, we now call as radio pulses or simply, the radio waves.
2
Maxwell proved that these electromagnetic disturbances should propagate in free space with
a constant speed equivalent to the speed of light 𝑐 = 3.0 𝑥 108 𝑚/𝑠 which can be calculated
using the formula below.
𝑐=
1
ඥ∈0− μ0
where:
𝑐 𝑖𝑠 𝑡ℎ𝑒 𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡
∈0 𝑖𝑠 𝑡ℎ𝑒 𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 𝑓𝑖𝑒𝑙𝑑 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
μ0 𝑖𝑠 𝑡ℎ𝑒 𝑚𝑎𝑔𝑛𝑒𝑡𝑖𝑐 𝑓𝑖𝑒𝑙𝑑 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
Source https://www.facebook.com/notes/physical-science/91-theory-of-special-relativity/3390893954260139/)
If we consider an object moving uniformly at 100 m/s (like Mr. Yap in the previous Activity)
and switch on a flashlight, according to Newtonian mechanics the speed of light would be 100
m/s + c and dispute Maxwell’s theory that calls for the speed of light to be constant. Which of
these two observations support the correct concept?
The Theory of Special Relativity proposed by Einstein in 1905, is a theory in physics that
concerns the relationship between space and time for objects that move uniformly near the
speed of light in a straight line. Simply put, an object approaching the speed of light would
make it’s mass infinite while reaching its cosmic limit and it is unable to go any faster than the
speed of light. It is generally accepted and is already experimentally confirmed based on two
main postulates.
The two main postulates of special relativity are:
1. The laws of physics are the same in all inertial frames of reference.
2. The speed of light in a vacuum is the same in all inertial reference frames.
These postulates imply that (1) Events that are happening at the same time for one observer
may not be simultaneous for another. (2) When two observers moving relative to each other
measure a time or space, they may not have the same results. (3) For the momentum and
energy to be conserved in all inertial systems, Newton’s Second Law and the equations of
momentum and kinetic energy must be revised.
What I Have Learned
Activity 4.1.2 Test your Analysis
1. Make a table showing the conflict between Newtonian Mechanics and Maxwell’s Theory
on the speed of light. Write your answer in your science notebook.
3
Maxwell’s Theory on Electromagnetism
Newtonian Mechanics
2. Explain in your own words how the theory of special relativity resolved the conflict
between Newtonian mechanics and Maxwell’s theory on electromagnetism.
3. What attitude or characteristics did the young Einstein have that led him to develop his
Theory of Special Relativity? How can you be like Einstein in this new normal?
What I Need to Know
Can you catch up with light then? What would happen if you are able to ride a light
beam? Or, if you move at the speed of light and check your face using a mirror, will you be
able to see your reflection? And If you travel through galactic space, will your wristwatch show
you Earth time?
Let us look closer at the two main postulates of Special Relativity.
Postulates of Special Relativity
1. The laws of physics are the same in all inertial frames of reference.
In an inertial reference frame, any object experiences no net force and so is considered
either at rest or moving uniformly with constant speed in the same direction. In this frame of
reference and without communication with the outside world, one cannot tell whether one is
at rest or one is moving with constant velocity. Therefore, all laws of nature are the same in
these inertial frames of reference.
If you measure the length of a 30 cm box with you on any ground or inside a bus
moving with constant velocity, you will get the same 30 cm measurement. Or if you swing a
pendulum on the ground or inside the uniformly moving bus and measure its period, you will
also have the same measurements when on either inertial frame of reference for the same
laws of physics are valid on each location.
If you do the same set of measurements with you at rest on the ground, while the box
and the swinging pendulum you are measuring are inside the uniformly moving bus, then this
time you will have measured different lengths for the box and periods for the pendulum. Being
aware now that you as an observer is relatively outside the inertial reference frame of the
object you are measuring, try as you might with being careful with your measurements, you
will always have a preference for one or the other.
Although the same laws of physics apply, now you must take into account the
relative transformations on time, space, matter and energy which become more pronounced
when the relative motion between the observer and the observed event or motion moves close
to the speed of light. This brings us to the second equivalent postulate.
4
2. The speed of light in a vacuum is the same in all inertial reference frames.
The second postulate means that for all reference frames, the speed of light, c is the
same no matter what the relative speed is between observer and that which is beingobserved,
be it moving matter, flowing energy or an event that occurs within invariantintervals of space
and time.
In other words, the speed of light is a universal constant in the natural world. Suppose
you are in a car going at 30 kph, and your cap flies off your head at 10 kph in the other direction
the car is going. If you were standing on the roadside with a radar gun, you would measure
the cap going 30 kph - 10 kph = 20 kph. That is how we classically (very lowspeeds compared
to light) deal with relative motion.
Now suppose you are in the car at night. If you could measure the speed of light coming
out of your headlights, you would get the same speed from the radar gun no matter how fast
the car was going forward or backward. Light would still be moving at its constant speed. That
is what makes light special!
What’s New
Activity 4.1.3 Guessing Time
Look at the picture in Figure 4.1.3. Why does the twin who travelled through space look
younger after 60 years than the twin that remained on earth? Does time on Earth differ with
the time in outer space? Why?
Figure 4.1.3 The Twin Paradox
One set of twins leaves the Earth in a rocket ship bound for the stars.
Sixty years later the rocket returns to Earth with the astronaut only 40 years old.
Source: http://abyss.uoregon.edu/~js/images/twin_paradox.gif
_
_
What Is It
Hi! I am back again, this time I am
sharing to you the different
consequences of Theory of Special
Relativity.
5
The consequences of the postulates of special relativity are (1) time dilation, (2)
length contraction, (3) relativity of simultaneity, (4) mass-energy equivalence, and (5) cosmic
speed limit.
TIME DILATION
An observer who is in relative motion with respect to a clock perceives the “slowing
down” of the clock.
Figure 4.1.4 The Consequence of Time Dilation
.
Consider a
light clock.
stationary
moving
Source: http://web2.uwindsor.ca/courses/physics/high_schools/2005/Special_relativity/TIMEDILATION.html
A clock measures the speed of light by sending out a beam of light to the top plate.
We will call this event A. The beam is then reflected to the clock as event B.
For the stationary clock on the left, the measured time interval between events A and
B is ten seconds. The clock on the right is set in motion with a given speed. To an observer
traveling with the clock, the time interval between events A and B is still ten seconds. However,
to an observer watching the clock move, it now appears that the light beam travels further than
before.
Since velocity is distance/time and the speed of this beam must be a constant, the
measured time interval between events A and B must now be greater than ten seconds. So,
to an observer on Earth, traveling clocks moved slower causing time to dilate or
increase. This is one of the consequences of special relativity.
LENGTH CONTRACTION
A moving object would be shorter in length as measured by stationary
observers. This is another consequence of special relativity.
Figure 4.1.5 The Consequence of Length Contraction
Here are two
identical cars
A and D.
Car A
Car B
Source: http://web2.uwindsor.ca/courses/physics/high_schools/2005/Special_relativity/car.jpg
6
Car A stops before a signpost while car B moved past it with an appreciable fraction
of the speed of light. Measure the length of car B while passing car A. Measure also the length
of car A. Is the length of car A the same as car B? It turns out that the length you measured
for car B will be shorter than the length of car A. This is an example of length contraction.
Relative to you, since car B is moving while car A is not, you obtained two different values for
their lengths.
Note that car B will only be shorter in length along the direction it is traveling, while its
width and height will not be affected. One cannot observe considerable length contraction
for objects or events that move very slowly in comparison to the speed oflight, not even
for objects moving at the speed of sound.
SIMULTANEITY
Two spatially separated simultaneous events do not necessarily occur at the
same time depending on the observer's reference frame. This is another consequence
of special relativity.
Figure 4.1.6 The Relativity of Simultaneity
Imagine that you and your
friend Timmy are standing on
opposite ends of the room
when you notice your teacher
turns on his penlight at the
podium. You ask Timmy if he
saw the teacher turn on the
light. Timmy answers that he
did.
Source: http://web2.uwindsor.ca/courses/physics/high_schools/2005/Special_relativity/2a.jpg
The next day your professor decides to demonstrate simultaneity by asking the class
to go inside the special relativity bus, while he remains outside midway the bus. Again, you
and Timmy are on opposite ends of the bus. Timmy sits in front with you at the back.
Then the bus starts moving at 0.9 c (90% the speed of light) while your stationary
professor outside turns on a Christmas lantern. With your watches synchronized, you and
Timmy separately took note of the moment when you saw the lantern turned on.
Source: http://web2.uwindsor.ca/courses/physics/high_schools/2005/Special_relativity/3c.jpg
7
When the bus comes to a stop you and Timmy compare the times at which you saw
the light. Surprisingly, you have different time records. Now that the bus was moving, the
backend was going into the path of the light waves faster than the light waves that were
spreading radially outwards from the middle of the bus. This enabled you to see the event
sooner, whereas Timmy had to wait for the emitted light waves to reach him. Thus, two
simultaneous events from a stationary observer (like the professor) are perceived as not
simultaneous relative to locations of moving observers.
MASS INCREASE
The rest energy and total energy of the body are equivalent
to the rest mass (an invariant quantity which is the same
for all observers in all reference frames) and relativistic
mass (dependent on the velocity of the observer),
respectively. This is the fourth consequence of special
relativity.
Figure 4.1.7 The Consequence of Mass Increase
Source: http://web2.uwindsor.ca/courses/physics/high_schools/2005/Special_relativity/MASSINCREASE.html
Einstein cleverly suggested that when someone measures your mass while you
are in motion, your mass will appear to increase as your speed increases.
So why does your mass seem to increase to an observer watching you if you are
speeding up? Einstein proposed that the energy 𝑬 is equivalent to the product of its rest mass
𝒎𝟎 and the square of the speed of light 𝒄𝟐 as indicated in Einstein’s famous equation 𝑬 =
𝒎𝒄𝟐. Your rest energy is a sort of minimum amount of energy you always have whether you
are at rest or not. This energy-mass equivalence is fundamental in many nuclear and particle
physics applications.
What I Have Learned
Activity 4.1.4 Explain Briefly
Answer the questions briefly and concisely.
1. During a flight to your engineering project site, it appears that the plane inside is at rest
with the Earth moving underneath your plane. Why is this view valid?
2. When will the observed elapsed time for a process seem longer? Is it when Observer A
is moving with the process? Or is it when Observer B is moving relative to the process?
Which observer measures proper time? Explain your answer.
3. How far can you travel into the future without aging significantly? Could this method also
apply to travels into the past?
4. To which observer will an object seem greater in length. Is it when Observer A is moving
with respect to the object? Or is it when Observer B is moving with the object? Which
observer measures the object’s proper length? Why?
5. Assuming no molecules escape or are added, what happens to the mass of water in a pot
when it cools? Is this observable in practice? Explain.
8
THE CONSEQUENCES OF THE
POSTULATES OF GENERAL
RELATIVITY
Lesson
2
What’s In
After the publication of the Theory of Special Relativity in 1905, the following years,
Einstein worked on the details that acceleration produced the same effect as gravitation. The
General Theory of Relativity is a generalization of the Special Theory of Relativity. It is the
most remarkable achievement of science to date. It was developed by Einstein with little or
no laboratory experiment but instead he was driven by mental analysis and philosophical
questions.
What I Need to Know
The General Theory of Relativity rests on the Principle of Equivalence which states
that inertial and gravitational (heavy) masses are identical. This postulate will fail if one can
find a material for which the inertial and gravitational masses have different values. One might
think that this represents a defect of the theory, its Achilles heel – its weakness despite its
overall strength. In one sense this is true since a single experiment has the potential of
demolishing the whole of the theory which many people have tried. On the contrary, all these
experiments validated instead of the principle of equivalence. Thus, the General Theory of
Relativity is a gem.
The second fundamental principle of General Relativity is that of the presence
of curve matter in space. With this principle, gravity is not classified as a force as described
by Newton, but a curvature in the fabric of space where matter, energy and time respond to
gravity by following the curvature of space in the vicinity of a massive object as illustrated in
Figure 4.2.1.
Figure 4.2.1 The Curvature of Space caused by a Massive Object.
Source: https://casswww.ucsd.edu/archive/public/tutorial/images/sp_curv.gif
What’s New
Activity 4.2.1. Find A Partner
Pair the following terms according to their meaning:
Bend
Process
Equivalent
Identical
Deflect
Shift
9
=
=
=
: which also means change
: which also means to follow a curve path
: which also means the same
Activity 4.2.2 The Fabric of Curvature
To visualize the curvature of space caused by a massive object, perform this activity
with your siblings, parents, or any household members.
Materials:
Any stretchable cloth or fabric such as a shirt, jersey, or blanket
Any round objects of considerably different masses available in your
home such as calamansi, onion, fruits, marble, ball, rock, etc.
Procedure:
1. Ask for assistance from any household members to hold on to the stretchable fabric on four
corners horizontally. (Placing your arms through the sides of a shirt will be adequate if there
is not much helping hand to perform the activity and learn with.)
2. Starting from a lighter object, place each round object on the center and observe what
happens to the fabric.
3. Continue with the next heavier objects.
4. Place any round object at the center of the fabric and this time, let another round object
roll on the fabric from any corner.
5. Do the same with the materials available.
Guide Questions:
1. What happened to the fabric as you place a round object at its center?
2. How does the mass of the round objects placed on the fabric affect its curvature?
3. How does the round object behave as it was rolled on the curved fabric?
What Is It
Some of the physical consequences of the postulates of general relativity that
will be introduced in this lesson are (1) shifts in the orbit of mercury, (2) gravitational bending
of light, and (3) black holes.
SHIFTS IN THE ORBIT OF MERCURY
In the study of the Solar System, a long-standing problem was that the orbit of Mercury
did not behave as Newton’s equations say. Let us look at the way Mercury’s orbit looks to
understand what the problem is.
As Mercury orbits the Sun, it approximately follows an elliptical path. It was foundthat
the point of closest approach of Mercury to the sun changes as it slowly moves around the
sun as shown in Figure 4.2.2. This rotation of the orbit is a precession. The precession
10
of the orbit does not happen to Mercury only but to all the planetary orbits. The effect of
being produced by the pull of the planets on one another was predicted in Newton’s theory.
The precession of Mercury’s orbit is measured to be 5600 seconds of arc per century
as seen from Earth. Considering all the effects from the other planets (as well as a very slight
deformation of the sun due to its rotation) and the fact that the inertial frame of reference is
not the Earth, the precession of 5557 seconds of arc per century has a discrepancy of 43
seconds of arc per century as predicted.
This discrepancy cannot be accounted for using Newton’s formalism. Many ad-hoc
fixes were devised (such as assuming that there was a certain amount of dust between the
Sun and Mercury) but none were consistent with other observations. Similarly, Einstein was
able to predict that the orbit of Mercury should process by an extra 43 seconds of arc per
century should the General Theory of Relativity be correct.
Figure 4.2.2. Artist’s Version of the Precession of Mercury’s Orbit. Most of the effect is due to the
pull from the other planets but there is a measurable effect due to the corrections to Newton’s theory
as predicted by the General Theory of Relativity.
Source: http://iontrap.umd.edu/wp-content/uploads/2016/01/WudkaGR-7.pdf page 179
GRAVITATIONAL BENDING OF LIGHT
A clear consequence of the equivalence principle is the bending of light by gravity. For
two times Einstein calculated the amount that light would be deflected while passing the sun,
which is the largest "nearby" mass (Figure 4.2.3). It was in his second calculation that Einstein
was able to predict that light from a distant star would be deflected by 1.75 arcseconds or less
than 1/2000th of a degree.
Figure 4.2.3 Bending of Light while Passing the Sun
Source: https://casswww.ucsd.edu/archive/public/tutorial/GR.html
11
The Solar Eclipse of 1919 was the first opportunity for Einstein to test his calculations.
British Astrophysicist Sir Arthur Eddington observed the shift in the position of the Hyades
cluster of stars behind the occulted sun by mounting a pair of expeditions to West Africa and
to Brazil. Though not perfectly precise, Eddington's measurements clearly showed a deflection
and favored the larger value. This result made Einstein world-famous.
This refers to the bending of light due to the change of the speed of light as it passes
through a refractive medium. Massive objects can act as lenses because gravity can bend
light. This is done by focusing on and amplifying images of distant objects. Gravitational lenses
differ from "normal" lenses. It produces multiple images such as the Einstein Cross, a case of
a distant quasar imaged behind a massive galaxy whose gravitational effect on the distant
quasar causes us to see this single object four times. The Einstein Cross was discovered by
J. Huchra & colleagues as shown in Figure 4.2.4.
Figure 4.2.4 The Einstein Cross: four images of a quasar GR2237+0305 (a very distant – 8
billion light-years– very bright object) appear around the central glow. The splitting of the central
image is due to the gravitational lensing effect produced by a nearby galaxy
Source: https://casswww.ucsd.edu/archive/public/tutorial/images/EinsteinCross.jpg
BLACK HOLES
Light is pulled by gravity just like rocks. Rocks can be put in orbits, but how about light?
Indeed, light can be put in orbits, but we need a very heavy object whose radius is very small
yet heavy, for example we need something as heavy as the sun but concentrated to a radius
of less than about 3 km.
Going farther and imagine an object so massive and compact that if we turn on a laser
beam on its surface, gravity’s pull will bend it back towards the surface. This means that since
no light can leave this object it will appear perfectly black. This is a black hole. An object
which comes sufficiently close to a black hole will also disappear into it since nothing moves
faster than light if an object traps light it will also trap everything else. A Black Hole is a large
body of matter that is so dense that nothing can escape its gravitational attraction.
The effect of a black hole, like all gravitational effects, decreases with distance. This
means that there will be a boundary surrounding the black hole that anything crossing it will
not be able to leave the region near the black hole; this boundary is called the black-hole
horizon.
12
What’s More
Activity 4.2.3. I am Bent
Refer to the two pictures below, how does the beam of light behave in both situations?
Situations
Behavior of light
(a)
Upward-accelerating
elevator
(b)
Elevator maybe
accelerating upward or
maybe acted by gravity
What postulate supports this behavior of light?
Source: https://openstax.org/books/college-physics/pages/34-2-generalrelativity-and-quantum-gravity
What I Have Learned
Activity 4.2.4 Expound Me
Describe the postulate and give a consequence.
Postulate 1.
_
_
Postulate 2
_
_
What I Can Do
Activity 4.2.5 Let Us React
Noting the different consequences of The Theory of General Relativity, what is
one of its great contributions to science and humanity?
13
Lesson
3
SPEEDS AND DISTANCES
OFFAR-OFF OBJECTS
What I Need to Know
Speeds and
distances of faroff objects…What
is this all about?
Hi! I am Mr. Starlight. I am going to
share to you what speeds and
distances of far-off objects is all about.
Oh, hi Mr. Starlight!
I really need
someone to teach
me about these.
Sure! I will teach you how
astronomers make
approximate determination of
distances and speeds of faroff objects in the universe.
Continue to read this module
and you will be able to explain
how the speeds and distances
of far-off objects are estimated
using Doppler Effect and
Cosmic Distance Ladder.
Do you remember that the astronomical unit AU
is a convenient unit of expressing distances in the
Solar System? It is the average distance
between the Earth and the Sun. One AU is 1.5 x
108 kilometers or 9.3 x 107 miles.
14
Using astronomical
units, one can get a
relative idea of the
distances of planets
from the Sun.
To measure distances to the nearest
solar system objects, scientists have
developed powerful radar to bounce
signals of Venus, Mars, Mercury, and
even the sun.
For more distant objects, astronomers use an
aged-old technique called geometric parallax
that was first devised by the Greeks in 300
BCE
What’s New
Activity 4.3.1 Knowing Parallax
Look at Figure 4.3.1. What did you
observe about the earth’s position
and a nearby star at different times
of the year? Write your observation
on your science notes.
Figure 4.3.1 Annual Parallax of a Nearby
Star
Source:
https://www.researchgate.net/profile/Spence_M_
Taylor/publication/235158031/figure/fig2/AS:299724398710804@1448471273699/The-astronomical-annualparallax-to-a-nearby-star-is-defined-as-the-half-angle-of-the_Q640.jpg
What Is It
The angle p,
measured in arc
seconds,
represents the
annual parallax
of the nearby
star.
Figure 4.3.1. shows the Annual Parallax
of a nearby star. This parallax effect is
due to the changing position of a viewer
as the Earth moves around the Sun. The
nearby star observed from two positions,
appears to move back and forth against
the background of more distant stars. This
apparent motion is called parallax.
15
The distance coordinate is measured in
light year (ly) or in parsec.
How is the distance
coordinate measured?
A light-year (ly) is the
distance traveled by light in 1
year (9.5 x 1012 km). It is
calculated by multiplying the
speed of light (3.00 x 105
km/s) by the number of
seconds in a year (3.16 x 107
s/y)
What is the difference
between a light year
and a parsec?
On the other hand, a parsec (pc) is defined as the distance to a star when the star
exhibits a parallax of 1 second of arc, where 1 second of arc is defined to be 1/3600 of
10. A parsec is related to a light-year by 1 pc = 3.26 ly
Defining a parsec this way provides an easy method for determining the distance to a
celestial object because taking the reciprocal of the angle p, measured in arc seconds,
gives the distance in parsecs.
distance (pc) = 1/parallax angle (p)
The distances to stars can also
be determined by knowing their
absolute andapparent
magnitudes.
These techniques are not
easy because the distance to
the star must be known to
determine the absolute
magnitude of the star.
Before 1915, the
technique of
accurately
measuring
distances were
limited to objects
within the Milky
Way Galaxy.
A breakthrough happened when Henrietta Leavitt, an
American astronomer discovered that a certain unstable
red giant Cepheid Variable Star could be used to
accurately measure distances.
Well, what did she
discover about the
Cepheid Star?
Leavitt found that the periods of variability of the
unstable stars were directly related to their brightness.
Therefore, the distances to the stars could be determined.
With this important discovery, the distance to the nearest
galaxies could be accurately determined. The use of
Cepheid variable stars (see Figure 4.3.2) allows accurate
measurements to 50 million light years.
16
Figure 4.3.2 Luminosity versus Period of Type I Cepheid Variable. (The period of variation in the
brightness of a Cepheid variable star is directly related to the brightness of the star, and the
distance can be determined using the graph.
Source: https://community.dur.ac.uk/physics.astrolab/images/maslumcep.gif
How about the distances to
more distant galaxies?
Astronomers in the 1970s discovered that the
brighter spiral galaxies (those having more stars)
rotate faster. Measuring rotation via the Doppler
shift of light allows one to determine the
absolute brightness of galaxy.
Distances up to 600 million
lightyears can be determined by
comparing the absolute and
apparent brightness of these
galaxies.
Is there a technique
that uses Physics
principle?
What is that inversesquare law of
intensity?
Supernovae can be used to measure distances
also, specifically Type I. Supernovae are stars that
explode and became incredibly bright objects,
sometimes entire galaxy of stars, or even brighter than
an entire galaxy of stars, although this will be so for a
short time.
Yes, many techniques use the
inverse-square law of intensity.
The inverse square law describes the intensity of light
at different distances from a light source. Every light
source is different, but the intensity changes in the
same way.
17
The intensity of light is inversely proportional to the
square of the distance.
1
𝑙𝑖𝑔ℎ𝑡 𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦, 𝐼 𝛼 2
17
𝑑
Where:
𝐼 = 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦 𝑤𝑖𝑡ℎ 𝑢𝑛𝑖𝑡𝑠 𝑜𝑓 𝑐𝑎𝑛𝑑𝑒𝑙𝑎 𝑜𝑟 𝑊Τ𝑚2
This means that as the distance
from a light source increases,
the intensity of light is equal to a
value multiplied by 𝟏Τ𝒅𝟐. The
proportional symbol α is used to
show how these are related.
The relationship
between the intensity of
light at different
distances from the same
light source can be
found by dividing one
from the other.
Visible light is part of the EM
spectrum, and the inverse square
law is true for any other waves or
rays on that spectrum like radio
waves, microwaves, infrared, x rays,
ultraviolet light, and gamma rays.
The intensity of visible light is
expressed in candela units while the
intensity of the other EM waves is
expressed in Watts per square
meter.
What about the
Intensity at different
distances?
The Intensity at different distances:
Where:
I1 = light intensity at distance 1
I2 = light intensity at distance 2
d1 = distance 1 from light source (m)
d2 = distance 2 from light source (m)
When astronomers use this principle to measure distances, they refer to the method as
standard candles. Because the brightness of the candle decreases as the square of
the distance increases, the distance to the candle is determined. The figure below
shows the simple idea for this technique.
Figure 4.3.3 The Standard Candle Technique.
18
As the candle is moved farther away, the brightness decreases. If the distance of the candle doubles,
then the brightness of the candle decreases by a factor of 4
Source: https://en.wikipedia.org/wiki/Cosmic_distance_ladder#Galactic_distance_indicators
19
Several methods rely on
a standard candle, which is an
astronomical object that has a
known luminosity.
Have you heard
about the
cosmic
distance?
ladder?
Yes sir. But
please tell me
more about it!
GREEN
GREEN
PURPLE
RED
GREEN
GREEN
GREEN
BLUE
BLUE
BLUE
BLUE
BLUE
PURPLE
BLUE
BLUE
BLUE
BLUE
BLUE
GREEN
BLUE
The cosmic distance ladder or extragalactic distance scale in Figure 4.3.4 is the
succession of methods by which astronomers determine the distances to celestial
objects. The ladder analogy below arises because there is no single technique that can
measure distances at all ranges encountered in astronomy.
Figure 4.3.4 The Cosmic Distance Ladder
Source: https://commons.wikimedia.org/wiki/File:Extragalactic_distance_ladder.JPG
Legend:
 Light green boxes
: Technique applicable to star-forming galaxies.
 Light blue boxes
: Technique applicable to Population II galaxies.
 Light Purple boxes
: Geometric distance technique.
 Light Red box : The planetary nebula luminosity function technique is
applicable to all populations of the Virgo Supercluster.
 Solid black lines
: Well calibrated ladder step.
 Dashed black lines : Uncertain calibration ladder step.
20
Instead, one method can be used to measure nearby
distances, a second can be used to measure nearby to
intermediate distances, and so on. Each rung of the
ladder provides information that can be used to determine
the distances at the next higher rung.
Is there a possibility to
have a direct distance
measurement of those
astronomical objects?
A real direct distance measurement of
an astronomical object is possible only
for those objects that are "close enough"
(within about a thousand
parsecs) to Earth.
Okay
At the base of the ladder
are fundamental distance
measurements, in which distances
are determined directly, with no
physical assumptions about the
nature of the object in question.
The precise measurement of stellar
positions is part of the discipline
of astrometry.
Now are you familiar
with Edwin Hubble?
Do you know what
Hubble’s Law is?
The name sounds
familiar…
Well, Edwin Powell Hubble, is an
American astronomer who played a
crucial role in establishing the field
of extragalactic astronomy and is
generally regarded as the leading
observational cosmologist of the
20th century.
What are his major
contributions?
Hubble’s Law determine distances to the
farthest known objects in the universe.
His major contributions are the following:
1. Using the new 100-inch telescope at Mt. Wilson Observatory in California, he
demonstrated that some of these nebulae, like the Andromeda nebula, were
actuallygalaxies far beyond our Milky Way Galaxy.
2. He was the first to classify galaxies based on what he observed from 1922 to
1923. He classified these based-on shapes (elliptical, spiral, and irregular) or a
galaxy’s visual morphology. Hubble’s classification led to his Hubble Galactic Tuning
Fork or Hubble Sequence (how he thought galaxies evolve).
3. His formulation of the redshift distance law in 1929, better known as Hubble’s
Law. The law states that the more distant a galaxy, the greater the redshift. We can
determine a galaxy’s receding velocity by its redshift— most of the time.
21
The velocity of many distant galaxies was
measured with large telescopes by observing
their spectra. The absorption lines in the
spectra are red-shifted (the well-known
Doppler effect) in direct relation to the overallvelocity of the galaxy.
How do velocities of
many distant galaxies
are measured?
Remember that the
Doppler effect is
observed whenever the
source of waves is
moving with respect to
an observer.
The produced effect by a moving source of waves
is an apparent upward shift in frequency for
observers towards whom the source is approaching
and an apparent downward shift in frequency for
observers
from whom the source is receding.
Now, let us talk about
Hubble’s Law.
Hubble’s law can be written in equation form as
�� = ��
Where,
𝑣𝑟 is the recessional velocity,
𝐻 is the Hubble’s constant
(currently estimated to be 71 km/s/MPc), and
𝑑 is the distance to the galaxy.
Thus, if a galaxy’s velocity is
measured to be 10, 000 km/s, then
��
�
Take note that to determine
distances to the most distant
objects in the universe, a very
good determination of the Hubble
constant is needed. The Hubble
𝑑=
10,000 𝑘𝑚/𝑠
𝑑=
71
space telescope does that very
task.
𝑘𝑚
/𝑀𝑝𝑐
𝑠
22
𝑑 = 141 𝑀𝑝𝑐 ≈ 460 𝑀𝑙𝑦
23
What’s More
Activity 4.3.2 Show It to Me!
Using Hubble’s Law equation, solve the following and show your solution. Box your final
answer.
1. The intensity of a radio signal is 0.120 W/m2 at 16.0 m from a small transmitter. What is the
intensity of the signal 4.00 m from the transmitter?
2. Galaxy NGC 123 has a velocity away from us of 1,320 km/s and the Hubble Constant's
value is 70 km/s/Mpc. How far away is the galaxy according to Hubble's Law?
What I Have Learned
Activity 4.3.3 Test Your Analysis
In the table below, write a summary of how to solve speeds and distances of far-off objects
on the first column and a brief explanation of the method/technique on the second column.
Method / Technique in solving distances
of far-off objects in the Universe
Explanation / Equation
Method / Technique in solving speeds of
far-off objects in the Universe
Explanation/Equation
What I Can Do
Activity 4.3.4 Make Me Complicated: Parallax
Answer the following:
Distance and parallax:
1. Recall what happened to the distance measured from the star as the parallax angle got
smaller. Briefly explain what happens to the distance as the parallax decreases.
2. Astronomers often measure parallax in units called arcseconds. There are 3600
arcseconds in 1 degree. Proxima Centauri, the nearest star to our Sun has a parallax of about
0.0002 degrees. How many arcseconds is this? Show your solution.
Parsec – the unit of distance:
3. One of the commonly used units of distance in astronomy is the parsec (pc), which comes
from combining the words parallax and second. Proxima Centauri is 4 x 1013 km (40 trillion
kilometers) from the Sun. Given that 1 pc = 3.1 x 1013 km, convert the distance of36 Proxima
Centauri into parsecs. Show your solution.
22
Distance to a star:
4. When parallax is measured in arcseconds and distance is measured in parsecs, the
formula relating distance, d and parallax, p is simply d = 1/p. WISE astronomers recently
discovered several brown dwarfs. These celestial objects were not massive enough to
become stars, is within 10 parsecs from our Sun.
(a) Find the distance to the brown dwarf, WISE 1541–2250, which has a parallax of 0.351
arcsec. Show your solution.
(b) Find the distance to the brown dwarf, WISE 0254+0224, which has a parallax of 0.165
arcsec. Show your solution.
23
Lesson
4
THE EXPANDING UNIVERSE
What’s In
Hi! I am teacher Beth, your teacher for this lesson,
‘The Expanding Universe’. How do you do today?
Hello teacher Beth. We are doing
fine today. Thank you.
That is great! In the previous
lesson, you have learned
how the distances and
speeds of far-off objects is
determined.
Using the knowledge that
you have; we will try to
discuss how the
astronomers determined the
structure of the expanding
universe we live in which
used to be hot and is
approximately 14 billion
years old. Cosmologywill
help us with this lesson.
By the way,
what is
cosmology?
Thoughts from
anyone? Yes
Ms. Sunshine?
24
Cosmology is
the branch of
astronomy that
deals with the
study of the
structure and
evolution of the
universe.
What I Need to Know
The astronomers determine the structure
of the universe by detecting and analyzing
electromagnetic waves that come from the
galaxies, the ‘building blocks’ of the universe.
What did they do
after detecting
and analyzing the
electromagnetic
Then, what
From the data collected,
they determine the way in
which these galaxies are
distributed throughout the
vast volume of the
universe.
happened next?
Astronomers then estimate the tens of
billions of galaxies that are within range
of the optical telescopes. Even if they
were inclined to do so, astronomers
would not have the time to observe all
the tremendous volume of the universe
for information about all the galaxies.
Ah, so the model
of the universe’s
structure was
based on
samples of
different regions.
Why? What did they do then?
A sampling of the different
regions of the universe was
used instead by the astronomers
to come up with the model of the
structure of the universe.
Yes definitely! These data also
revealed large voids, millions of
light-years across space that
contained very few galaxies. In
other words, the two-dimensional
sheets were separated by vast
volumes of nearly empty space.
So it seems that galaxies are not
evenly distributed in space.
25
In 2003, a team of astronomers, entered the
coordinates into the computer, and obtained
an illustration showing the location and
relative positions of different galaxies.
Based on it, they found out that
nearly every galaxy in the
sample belongs to either a twodimensional “sheet” or a onedimensional “thread” that is
millions of light-years in length.
So, from what was shown
in the illustration, what was
their finding?
Millions of light-years in
length? That is very far!
Yes, exactly!
What’s New
Activity 4.4.1 Think and Share
Read each question carefully. Think critically and share your answer by writing it in a
clean sheet of paper.
1. What is the universe expanding into?
_
_
2. Is the universe becoming into something?
_
What Is It
Does the universe
go on forever, or
does it have an
edge somewhere?
Guys, your questions are
also the basic questions
about the size and age of
our very universe that
astronomers wrestled with
for thousands of years.
Has it always
existed, or did it
come to being at
some time in the
past?
26
_
_
Mr. Hubble discovered that
the universe is expanding!
Remember the
astronomer Edwin
Hubble? He made
a critical discovery
that led to scientific
answers to your
questions?
When Einstein developed his
General Theory of Relativity,
he thought he ran into the
same problem that Newton
did. His equations imply that
the universe should be either
expanding or collapsing, yet
he assumed prematurely
that the universe was static.
Well, you see, Einstein’s
original solution contained a
constant term, called the
cosmological constant, which
cancelled the effects of
gravity on very large scales,
and led to a static universe.
So, after Hubble discovered
that the universe was
expanding, Einstein called the
cosmological constant his
"greatest blunder."
Einstein's theory of gravity
discovered the equations had
some solutions that described an
expanding universe. In these
solutions, the light coming from
distant objects would be
redshifted as it traveled through
the expanding universe. The
redshift would increase with
increasing distance to the object.
Really?
Yes!
Ma’am, can you tell us the story
on how Mr. Hubble discovered
that the Universe is expanding?
Sure! That is good! You
guys are listening
intently…
In 1929 Edwin Hubble, working at
the Carnegie Observatories in
Pasadena, California, measured the
redshifts of distant galaxies. He also
measured their relative distances by
measuring the apparent brightness
of a class of variable stars called
Cepheids in each galaxy.
Remember the Cepheids Variables?
When he plotted Doppler redshift
against relative distance, he found
that the redshift of distant galaxies
increased as a linear function of their
distance. The only explanation for
this observation is that the universe
was expanding.
Same finding
with Einstein…
27
Once scientists understood that the
universe was expanding, they
immediately realized that it would have
been smaller in the past. At some point
in the past, the entire universe would
have been a single point and must have
been more compressed. Carrying this
idea to each logical conclusion, most
astronomers think that the universe
began in a small, hot, dense state, the
rapid expansion of which is called the
Big Bang and was the beginning of the
universe as we understand it today.
Teacher Beth can
you please give us
an illustration on
how the universe
expands?
Ah! Like a
bubble…
gum?
looks like an
Of course, Jupiter, why not?
That’s the reason why I am
here today…for you to
learnnew things each day
and because of that very
kind request, I will see to it
guys that you will go home
with great learning. So hold
on and concentrate!
Big bang
as in big
explosion?
Can you please
illustrate to us
how the universe
expands?
If the galaxies are
moving away from one
another at the present
time, the galaxies must
have been closer to one
another in the past.
That is, the universe.
Consider baking a loaf of raisin bread. Imagine that the raisins represent the
galaxies and the dough represents space. As the loaf bakes and expands, its
raisin remains the same size but moves away from every other raisin. No
matter which raisin an observer might be “riding”, the other raisins would move
away. The greater the initial distance a specific raisin was from the observer’s
raisin, the faster and the farther the observed raisin would recede.
28
Figure 4.4.1 Analogy of the Expanding Universe
Source:https://courses.lumenlearning.com/astronomy/chapter/the-expanding-universe/
The expanding universe is somewhat analogous to the expanding dough in a
loaf of a raisin bread (See Figure 4.4.1). The raisins (representing the galaxies)
are carried along as the dough (space) expands. The number show that the
farther an observer “raisin” the faster the former is moving.
Note that the raisins “galaxies” stay the
same size, but they are carried along
by the expansion of the dough (space).
Essentially, the raisins behave in
accordance with Hubble’s law.
So, if that is
the case,
how old is the
universe
now?
Maybe it is
very hard to
determine the
age of our
universe…
No Venus, we can
calculate the age of
the universe easily.
That will be our next
topic.
Whoaah!!! Sounds interesting!
Really interesting, but how?
Until recently, astronomers estimated that the Big Bang occurred
between 12 and 14 billion years ago. To put this in perspective,
the Solar System is thought to be 4.5 billion years old and
humans have existed as a genus for only a few million years.
29
Astronomers estimate the age of the universe in two ways:
by looking for the oldest stars; and
by measuring the rate of expansion of the universe and
extrapolating back to the Big Bang; just as crime
detectives can trace the origin of a bullet from the holes in
a wall.
Astronomers can use a simple technique to determine the
age of the universe by using Hubble’s law (See Figure 4.4.2).
Figure 4.4.2 Velocity–distance relation among extragalactic nebulae (1).
Source: https://www.pnas.org/content/112/11/3173
“Radial velocities, corrected for solar motion, are plotted against distances estimated
from involved stars and mean luminosities of nebulae in a cluster. The black discs and
full line represent the solution for solar motion using the nebulae individually; the
circles and broken line represent the solution combining the nebulae into groups; the
cross represents the mean velocity corresponding to the mean distance of 22
nebulae whose distances could not be estimated individually” (1).
(Note: Velocity units should be in kilometers per second.)
As shown in the figure above, the slope of the graph
represents the assumed constant rate at which the universe
is expanding; therefore, astronomers can calculate how long
the universe has been expanding, and the result of that
calculation is the age of the universe.
30
This relation is the
well-known Hubble
Law (and its graphic
representation is the
Hubble Diagram)
It is like this, if the slope of the line is the Hubble
constant 𝑯, then the age of the universe is
𝑨𝒈𝒆 𝒐𝒇 𝒕𝒉𝒆 𝒖𝒏𝒊𝒗𝒆𝒓𝒔𝒆 ሺ𝒚𝒓ሺ −
𝟗. 𝟕𝟖 𝒙 𝟏𝟎𝟏𝟏
𝑯
where:
𝑯 is the Hubble constant currently estimated to be
71 kilometer/second/Megaparsec or km/s/Mpc.
What does 9.78 x 1011
stands for?
The number 9.78 x 1011 is a
conversion factor for the time and
distance units used in the
problem. The best estimate of the
constant H is about 71 km/s/Mpc
(1 Mpc = 1 mega-parsec, 1 million
parsecs). This calculation gives
about 13.8 billion years for the
age of the universe.
Do astronomers agree
that the universe is
expanding?
Recent evidence strongly
indicates that we live in what
cosmologists call a flat
universe that will continue to
expand forever. Contrary to
earlier ideas that gravity would
slow down the expansion.
Yes definitely!
Will it
expand
forever?
Is there any
confirmatio
nfor this
ma’am?
Yes! Recent discoveries have
confirmed that the expansion of the
universe is actually accelerating. The
acceleration is thought to be due to the
repulsive effect of a mysterious dark
energy that seems to make up 68% of
the mass-energy of the universe
(E=mc2). The remaining mass energy
appears to be 5% ordinary matter and
27% dark matter.
31
What’s More
Activity 4.4.2 The Expanding Universe-Galaxies
Follow the step-by-step instructions.
1. Take a round balloon and draw on it six “galaxies”, each about 5 mm across. Make your
galaxies roughly evenly spaced around the balloon.
2. Choose any one of the “galaxies” and mark it “A” so that you remember which it is. Label
also the other “galaxies.” Make a mental note of the distances from this galaxy A to its
nearest neighboring galaxies.
3. The balloon represents space itself. Blow up the balloon to represent the expansion of the
universal space.
4. Again, check the distances from galaxy A to its nearest neighbors.
5. Answer the following questions in complete sentences:
a. Sketch the balloon with its galaxies before and after you blew it up. Observe and record
your observation.
b. If people living somewhere in galaxy A. observe the motion of their neighbor galaxies, what
will they notice? Why might they think their own galaxy is the center of the universe?
c. Would people in a different galaxy observe the same over-all effect in the motion and
location of a neighboring galaxy, or would they observe something different?
d. As time goes by, the real universe behaves much more than like this balloon. What do you
think our astronomers must have observed about the motion of our neighboring galaxies?
What I Have Learned
Activity 4.4.3 Test Your Analysis - Calculating the Age of the Universe
In a clean sheet of paper, calculate the age of the universe if the constant rate of
expansion is 71 km/s/Mpc. Show your solution.
32
What I Can Do?
Activity 4.4.4 Sketch Me Up!
Using one letter-sized (short) bond paper, draw your understanding of an expanding
universe. Make it colorful and presentable.
SUMMARY
1. Angle p is measured in arc seconds. It represents the annual parallax of the nearby star.
2. Astronomical unit AU. A convenient unit of expressing distances in the solar system. It is
the average distance between the Earth and the Sun. One AU is 1.5 x 108 km (9.3 x 107 mi).
3. Big bang. The idea most astronomers think that the universe began in a small, hot, dense
state, and is rapidly expanding and was the beginning of the universe.
4. Black Hole. A region of spacetime where gravity is so strong that nothing—no particles
or even electromagnetic radiation such as light—can escape from it.
5. Cepheid variable stars. Unstable red giant stars could be used to accurately measure
distance up to 50 million ly.
6. Cosmic distance ladder (also known as the extragalactic distance scale). The
succession of methods by which astronomers determine the distances to celestial objects.
7. Cosmology. The branch of astronomy that deals with the study of the structure and
evolution of the universe.
8. First Postulate of special relativity. At any frame of reference, all laws of physics are
similar.
9. Geometric parallax. An age-old technique used by astronomers for more distant objects
was first devised by the Greeks in 300 BCE.
33
10. Gravitational Lensing. The bending and focusing of light and especially the formation
of multiple images of a more distant object by a celestial object acting as a gravitational
lens.
11. Hubble’s law. A simple technique used by astronomers to determine the age of the
universe. If the slope of the line is the Hubble constant 𝑯, then the age of the universe is
𝟗. 𝟕𝟖 𝒙 𝟏𝟎𝟏𝟏
𝑨𝒈𝒆 𝒐𝒇 𝒕𝒉𝒆 𝒖𝒏𝒊𝒗𝒆𝒓𝒔𝒆 ሺ𝒚𝒓ሺ −
𝑯
where: 𝑯 is the Hubble constant currently estimated to be
71 kilometer/second/Megaparsec or km/s/Mpc
(1 Mpc = 1 mega-parsec, 1 million parsecs).
12. Inverse-square law. A technique that uses the Physics principle to describe the intensity
of light at different distances from a light source. The intensity of light is inversely proportional
to the square of the distance.
13. Length of Contraction. A moving object would be shorter in length as observed by the
observer at rest that is relative to the moving object.
14. Light-year (ly). The distance traveled by light in 1 year (9.5 x 1012 km, 6 trillion mi.).
15. Mass Increase. The rest energy and total energy of the body are equivalent to the rest
mass (an invariant quantity which is the same for all observers in all reference frames) and
relativistic mass (dependent on the velocity of the observer), respectively.
16. Maxwell Theory. The light in a vacuum travels at a constant speed regardless of the
motion of the source or the observer.
17. Newtonian Mechanics. The speed of light depends on the motion of the observer and
the light source.
18. Number 9.78 x 1011. A conversion factor for the time and distance units used in the
problem
19. One parsec, (pc). The distance to a star when the star exhibits a parallax of 1 second of
arc, where 1 second of arc is defined to be 1/3600 of 10. A parsec (pc) = 3.26 ly.
20. Parallax. The apparent motion of the nearby star observed from two positions, which
appears to move back and forth against the background of more distant stars
21. Precession. The change in the orientation of the rotational axis of a rotating body.
22. Second Postulate special relativity. For all reference frames, the speed of light (c) is
the same no matter what their relative speed is.
23. Simultaneity. Whether two spatially separated events not absolute occur at the same
time but depends on the observer's reference frame.
24. Standard Candle Technique. The other term for the inverse square law. As the candle
is moved farther away, the brightness decreases. If the distance to the candles doubles,then
the brightness of the candle decreases by a factor of 4.
25. Time Dilation. An observer who is in relative motion with respect to that clock determined
the “slowing down” of a clock.
34
Assessment (Posttest)
Multiple Choice. Select the letter of the best answer from among the given choices.
1. Einstein’s Theory of Special relativity is based on what two postulates? Choose all that
apply.
I. The laws of physics are the same in all inertial frames of reference moving with
constant velocity relative to one another.
II. The laws of physics application change based on the condition of the observer.
III. The speed of light is constant in all inertial frame of reference.
IV. The speed of light depends on the speed of the observer.
A. I only
C. II and IV
B. I and II
D. I and III
2. Which of the following describes the speed of light according to Newtonian mechanics?
The speed of light in any frame of reference
A. is infinite.
C. depends on the observer’s motion.
B. is constant.
D. depends on the motion of its source.
3. Which of the following correctly describes the statement: The speed of light is constant?
A. The statement is sometimes true.
C. The statement is never true.
B. The statement is always true
D. The statement is sometimes false.
4. A woman on the ground sees a rocket moving past her at 99% the speed of light.
Compared to when the rocket is at rest, the woman measures the length of the
moving rocket as:
A. longer.
C. a foot long.
B. shorter.
D. having the same length.
5. Starship "Alpha" travels at 0.9c past an identical starship "Beta," which is at rest. Both a
cabin boy on the "Alpha" and a cook on the "Beta" measure the time required for the other
ship to pass by their respective windows. Who measures the longer time?
A. Both measure the same time.
C. the cabin boy
B. Time stood still.
D. the cook
6. Two identical clocks are made. One is placed in interstellar space, and the other is
placed on the surface of a massive planet. Which runs faster?
A. Both clocks have the same rate.
C. the planet clock
B. Both clocks stopped running.
D. the space clock
7. Which of the following describes the first postulate of General Relativity Theory?
A. Inertial and gravitational masses have different values.
B. Inertial and gravitational masses are identical.
C. Inertial and gravitational masses are inversely proportional.
D. Both inertial and gravitational masses are zero.
8. Which of the following is NOT a consequence of the General Theory of Relativity?
A. Black hole
C. Precession of Mercury’s orbit
B. Red Giant
D. The existence of gravitational lenses
35
9. Why is a blackhole black?
A. No light can escape the blackhole.
B. No light can enter the blackhole.
C. All colors are absorbed by the blackhole.
D. All colors are reflected off the blackhole.
10. Who discovered that Cepheid variable stars could be used to accurately
measuredistances?
A. Alan Guth
C. Albert Einstein
B. Edwin Hubble
D. Henrietta Leavitt
11. Calculate the number of seconds in a year (365 days) in standard exponential
notation with three significant figures.
A. 3.51 x 107 s/yr
C. 3.51 x 109 s/yr
7
B. 3.15 x 10 s/yr
D. 3.15 x 109 s/yr
12. What do you call the age-old technique used by astronomers to determine
distantobjects?
A. Parallax
C. The standard candle
B. Doppler Effect
D. Cepheid variable stars
13.What happens to the brightness of the candle when the square of its distance
decreases?
A. It increases.
C. It remains the same.
B. It decreases.
D. It becomes zero.
14. A galaxy cluster in Ursa Major has a recessional velocity of 15, 000 km/s. Using
the bestestimate for Hubble’s constant, find the distance to the galaxy cluster.
A. 112 Mpc
C. 211 Mpc
B. 121 Mpc
D. 221 Mpc
15. One cannot directly observe blackholes because they emit no light. Why can
scientistsstill hunt or track them?
A. A black hole can radiate electrons. C. A black hole can affect orbits of nearby
stars.
B. A black hole can reflect protons.
D. A black hole can radiate high-speed
photons.
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