6.9C: Energy Transformations
Force, Motion, and Energy
TEKS UNWRAPPED
The student knows that the Law of Conservation of Energy states that energy can neither be created nor
destroyed, it just changes form. The student is expected to:
Demonstrate energy transformations such as energy in a flashlight battery changes from chemical
energy to electrical energy to light energy. (Supporting Standard)
Prior Knowledge/TEKS
4.6 A: Differentiate among forms of energy including mechanical, sound, electrical, light, and heat/thermal.
5.6 A: Explore the uses of energy including mechanical, light, thermal, electrical, and sound energy.
5.9 B: Describe how the flow of energy derived from the Sun, used by producers to create their own food,
is transferred through a food chain and food web to consumers and decomposers.
Key Concepts
•
•
Energy is neither created nor destroyed; it changes from one form to another.
There are many different forms of energy, such as chemical energy (energy stored in bonds between
•
atoms), electrical energy (energy of electric currents), and light energy (energy of electromagnetic
waves).
Energy transformations occur regularly in our lives, such as when we use a flashlight (chemical to
electrical to light energy), light a match (chemical to light energy), or digest food (chemical to thermal).
Food chains and food webs are also examples of an energy transformation as radiant energy is
•
transformed to chemical energy in plants, and chemical energy is transformed into mechanical energy
(movement) in animals.
Fundamental Questions
•
•
Why are energy transformations important to everyday life?
How is chemical energy transformed to electrical energy in a battery?
•
How do we use transformations of electrical energy?
■
2012 e Rice Universa ,, - All Rights Rese
.
6.9C: Energy Transformations
Force, Motion, and Energy
TEKS UNWRAPPED
Dissecting TEKS Nouns
energy
chemical energy
transformation
battery
electrical energy
light energy
bond
atom
electric current
electromagnetic wave
mechanical energy
radiant energy
Dissecting TEKS Verbs
Demonstrate
1. To show or explain how something is used or done
2. To prove something by showing examples of it
Bloom's Taxonomy: Comprehension
Bloom's Revised: Understand
Prompts at the UNDERSTAND level include:
Interpret, Exemplify, Explain, Demonstrate, Translate, Summarize, Compare, Infer, Classify
How will your students UNDERSTAND the concepts in 6.9C TEKS?
Examples of prompts for this level of content knowledge include:
•
•
Explain how energy from the Sun can be transformed to be usable to animals.
Give examples for each of the following energy transformations: chemical to electric; mechanical to
thermal; electric to thermal.
Definition Source: Merriam Webster Dictionary
'2012
in
Rice Uniwr ity - All
Reserved
6.9C: Energy Transformations
Force, Motion, and Energy
TEKS UNWRAPPED
Released SAMPLE STAAR ITEM
TEKS: 6.9C, Answer (B)
Wind Turbine System
Blades
1
Wind energy
turns
blades of
wind
turbine
2
KR.,tating
blades
u rn rotor in
lenerator
Generator
4
3
Energy moves
from generat
into powt
Ines
Energy moves
f )ugh power 1 nes
Energy from
power tines
. - auses filaments
in toaster to
glc
Power lines
ixr roar tr
In the diagram above, 3 wind turbine is transforming energy from the wind. Between which
two steps n the diagram is mechanical energy being converted into electrical energy?
A 1 ancl 2
B
2 and 3
C
3 and 4
D
-4 and 5
...-' 201
2In
• Ricci iniversitv - An RightsReserved
Reseed
8th Grade Science 6.9C
Date
Name
Class/Grade
1
Expectation: 6.9(C)
Which of the following best describes the type of energy transformation that occurs
during photosynthesis?
2
A
Chemical energy is transformed into magnetic energy.
B
Thermal energy is transformed into light energy.
C
Light energy is transformed into chemical energy.
D
Electrical energy is transformed into mechanical energy.
Expectation: 6.9(C)
An electric car transforms electrical energy into —
F
mechanical energy and light energy.
G
sound energy and chemical energy.
H
nuclear energy and light energy.
3
heat energy and chemical energy.
©1999-2012 Progress Testing
Page 1
8th Grade Science 6.9C
3
Expectation: 6.9(C)
The diagram below shows a solar cell.
sunlight
front
contact
anti-reflective
\
coating
specially treated
semi-conductor
material
back contact
Courtesy of NASA, 2011
At what point is light energy transformed into electrical energy?
A
2
B
3
C
1
D
4
©1999-2012 Progress Testing
Page 2
8th Grade Science 6.9C
4
Expectation: 6.9(C)
When electric power is carried over long distances through power lines, the electrical
energy decreases as the distance increases. This energy decrease occurs because the
current encounters resistance in the wires. Which of the following best describes what
happens to the missing electrical energy?
F
The energy is transformed into electromagnetic energy and is released as
microwaves.
G
The energy is transformed into thermal energy and is released into the
atmosphere.
H
The energy is transferred to the current's electrons as the power lines are
grounded.
3 The energy is transferred to the air as light energy as it travels along the power
line.
5
Expectation: 6.9(C)
A wood fire transforms the chemical energy stored in wood into —
A
light energy.
B
mechanical energy
C
electrical energy.
D
nuclear energy.
©1999-2012 Progress Testing
Page 3
8th Grade Science 6.9C
6
Expectation: 6.9(C)
Coal is the fuel source used to power steam engines. Which statement best describes
the energy transfer that takes place in a train powered by a steam engine?
7
F
Some of the coal's chemical energy is transformed into mechanical energy, and
some is released as heat and light.
G
Most of the coal's chemical energy is destroyed as the coal is burned.
H
Most of the coal's electrical energy is captured and used to power the train.
3
All of the coal's electrical energy is lost as heat and light when it is burned.
Expectation: 6.9(C)
Fireworks transform chemical energy into —
8
A
mechanical energy and electrical energy.
B
sound energy and electrical energy.
C
nuclear energy and sound energy.
D
heat energy and light energy.
Expectation: 6.9(C)
A radio is a device that converts energy from one form to another. Which of the
following best describes the energy conversion process that takes place in a radio?
F
Sound is created by energy stored in the speakers.
G
Electrical energy is converted into sound energy and heat energy.
H
Some energy is released as sound, and the rest is destroyed.
3
Electrical energy is converted into chemical energy and sound energy.
©1999-2012 Progress Testing
Page 4
8th Grade Science 6.9C
9
Expectation: 6.9(C)
Which of the following is an example of a transformation of chemical energy into
electrical energy?
A
Sunlight providing power to a solar calculator
B
A blowtorch welding two pieces of metal together
C
An oil lamp lighting up a room
D
A car battery making headlights shine
10 Expectation: 6.9(C)
A construction worker swings a hammer and hits a nail. After the hammer hits the
nail, mechanical energy is transformed into —
F
light energy.
G
electrical energy.
H
heat energy and sound energy.
3
wind energy and nuclear energy.
11 Expectation: 6.9(C)
A windmill transforms the mechanical energy of the wind into —
A
chemical energy.
B
light energy.
C
electrical energy.
D
nuclear energy.
©1999-2012 Progress Testing
Page 5
8th Grade Science 6.9C
12 Expectation: 6.9(C)
A microwave transforms electrical energy into —
F
heat energy, light energy, and sound energy.
G
light energy and sound energy only.
H
heat energy and sound energy only.
J
heat energy only.
13 Expectation: 6.9(C)
A computer monitor transforms electrical energy into —
A
mechanical energy and heat energy.
B
chemical energy and nuclear energy.
C
light energy and heat energy.
D
sound energy and nuclear energy.
14 Expectation: 6.9(C)
An oven transforms electrical energy into —
F
nuclear energy and mechanical energy.
G
heat energy and light energy.
H
chemical energy and sound energy.
3 light energy and sound energy.
©1999-2012 Progress Testing
Page 6
8th Grade Science 6.9C
15 Expectation: 6.9(C)
A water wheel transforms mechanical energy into —
A
nuclear energy.
B
light energy.
C
chemical energy.
D electrical energy.
©1999-2012 Progress Testing
Page 7
8th Grade Science 6.9C
Date
Name
Class/Grade
DIRECTIONS FOR MARKING ANSWER SHEET
Use a #2 pencil only.
Do NOT use ink or ballpoint pens.
Make heavy black marks that fill the ovals completely.
Erase clearly any answer you wish to change.
Make no stray marks on the answer sheet.
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©1999-2012 Progress Testing
8th Grade Science 6.9C
Instructions to read aloud to your students.
When you decide what the answer to a question is, mark your answer on your answer sheet. To do so,
find the row of circles with the same number as the question. Then darken in the circle with the same
letter as the answer you chose. If you don't know the answer to a question, skip it. You may return to it
later if you have time. If you finish the test early, you should go back and check over your work. Do NOT
fold your answer sheet or make any stray marks.
When marking your answer sheet:
1. Make a heavy mark. The mark should be large enough to fill the circle, but it should not go outside too
much. Do not waste time making very neat marks. It is more important to make very dark marks. Be sure
to use a #2 pencil.
2. Be sure that your mark for every question is placed in the row with the same number as that question.
3. Make only ONE mark in a row. If you change your mind about an answer, erase your first mark as
completely as you can.
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Name:
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Date:
STAAR Science Tutorial 17
TEK 6.9C: Energy Forms & Conversions
TEK 6.9C: Demonstrate energy transformations such as energy in a flashlight
battery changes from chemical energy to electrical energy to light
energy.
Energy Forms
•
Energy is the ability to do work or cause change. Unlike matter, energy does not
have mass or take up space. It is visible only through the motion of matter or
other changes to matter that it causes.
•
As discussed in Tutorial 13: Potential and Kinetic Energy, energy can be classified
into two broad categories, kinetic energy (energy presently performing work) and
potential energy (stored energy not presently performing work).
•
Energy can also be classified by its energy form, the physical appearance that it
takes when observed interacting with matter. Energy form is a different
classification category from the kinetic-potential classification category. Just as
people can be classified by gender (male or female), age or by race, so too can
energy be classified both by form, as discussed in this tutorial, and by its active or
stored state, as discussed in Tutorial 13.
•
Energy is found in six different forms: mechanical energy, chemical energy, thermal
energy, electrical energy, radiant (or electromagnetic) energy, and nuclear energy:
•
Mechanical energy, in its kinetic, working state, is the energy of motion of
large objects, or the motion of a mass of particles moving in unison. A
moving car, wind, ocean wave, earthquake or sound wave are all examples of
kinetic mechanical energy. In the potential, stored state, mechanical energy
is the energy stored in large objects or a mass of particles, because of their
position, such as height above the ground (gravitational potential energy), or
stored in its internal condition, such as compression or tension (elastic
potential energy). A body of water stored behind a high dam, and a roller
coaster car sitting at the top of the hill, are examples of gravitational
potential energy. A compressed spring, stretched rubber band, and
deformed rock along a fault line, which when released causes an earthquake,
are all examples of elastic potential mechanical energy.
•
Chemical energy is the energy stored in the bonds between atoms, such as
ionic or covalent bonds. Chemical energy is always potential energy, never
kinetic energy, because the chemical energy form must be converted to
another form before it can do work or be observed as causing change. Every
chemical reaction either stores chemical energy (endothermic reactions) or
releases energy (exothermic reactions). The photosynthesis chemical
reaction in plants uses radiant energy from sunlight and converts and stores
that energy in the atomic bonds within the sugar created by the plant. When
that sugar is eaten by an animal and digested, the cellular respiration
reaction breaks the atomic bonds in sugar and converts the chemical energy,
usually into thermal energy or mechanical energy.
•
Thermal energy is the energy of vibrational motion in atoms and molecules.
The greater the rate of vibration, the greater the thermal energy the particles
have. Thermal energy is measured as temperature. Any atom or molecule
above absolute zero (-273°C) has thermal energy. The vibration of thermal
energy is why substances have a melting point and a boiling point. Matter
with low thermal energy is found as a solid—there is not enough vibration
(thermal energy) to allow the atoms to move around in relation to one
another. As the thermal energy increases, the atoms vibrate more and can
move around more easily—the solid melts into a liquid. As still more thermal
energy is added, the atoms vibrate so violently that they can leave their
container and fly around as a gas. Most energy transformation processes
eventually produce thermal energy as the final energy form.
•
Electrical energy is the energy found in charged particles—protons (+) or
electrons (-). If the charges are not moving, we call it static electricity
(potential energy). Examples of static electrical energy are the charge a
person picks up when walking across carpet, charges in a cloud just before a
lightning discharge, and the charge stored in a capacitor in an electrical
circuit. If the particles (usually electrons) are moving through a conductor, it
is an electrical current (kinetic energy). Electrical energy is easy to
transport, and can easily be converted into other energy forms. For this
reason, modern civilization is built around electric generation and electrical
devices such as motors and computers.
•
Radiant or electromagnetic energy is the only form of energy that does
not need matter to be transmitted. Radio waves, microwaves, infrared
waves, visible light, ultraviolet light, x-rays and gamma rays are all types of
radiant or electromagnetic energy, differing only in their wavelengths.
Electromagnetic waves move at a very fast constant speed (the "speed of
light"), and thus can only be kinetic, not potential, energy.
•
Nuclear energy is the energy stored in the nucleus of atoms released either
in the nuclear fusion (fusing two nuclei into one nucleus) or fission (breaking
one nucleus into two nuclei). The sun uses nuclear fusion to create other
energy forms. Nuclear electric power plants use nuclear fission to create
other energy forms.
Law of Conservation of Energy
•
The law of conservation of energy states that energy cannot be destroyed, but
only transformed (converted) into different forms. For example, when sunlight
(radiant energy) falls on a plant, the chlorophyll within the plant converts the
radiant energy into chemical energy, stored in the atomic bonds of the sugar
produced by photosynthesis. The mechanical energy of motion, such as in a roller
coaster car, is usually transformed into thermal energy by friction (a force that
opposes motion).
Energy Transformations
•
In stars and our Sun, nuclear energy is transformed by the nuclear fusion process
(fusing four hydrogen nuclei into one helium nucleus) into electromagnetic /
radiant energy. This electromagnetic (radiant) energy can travel through the
vacuum of space to Earth, where it is transformed (converted) into other energy
forms.
•
Sunlight, which is electromagnetic / radiant energy, strikes the Earth's surface and
greenhouse gas molecules in the atmosphere, and are transformed into thermal
energy, as the Earth is warmed by sunlight.
•
As thermal energy is transferred by conduction from the land surface to air
molecules, the air becomes less dense and rises, thus transforming some of the
thermal energy into mechanical energy (convection currents and wind).
•
When sunlight (electromagnetic / radiant energy) falls on a plant leave containing
chlorophyll, the radiant energy is converted into chemical energy stored in the
chemical bonds between the atoms in sugar, assembled from the carbon, oxygen
and hydrogen atoms from water and carbon dioxide. This is the photosynthesis
reaction.
•
When animals eat plants and the sugar they contain, the chemical energy is
converted into either mechanical energy (movement of the animal) or thermal
energy (body heat). A small amount of the chemical energy is also converted into
electrical energy for the nervous system. Some animals, such as fireflies and
deep-sea fish, can convert chemical energy into light (electromagnetic energy).
•
In a flashlight, chemical energy in the batteries is converted to electrical energy
when the circuit including the batteries, switch and light bulb is completed. The
electrical energy is converted to light (electromagnetic / radiant energy) and some
heat (thermal energy) by the light bulb.
•
In an electric motor, electrical energy is converted to motion (mechanical energy)
and some heat (thermal energy).
•
In a gasoline engine such as those found in an automobile, the chemical energy in
the gasoline is converted into thermal energy (heat) when it burns, which in turn
expands the gases in the cylinder and turns the engine (mechanical energy),
moving the car.
•
In a wind-powered electric generator, the wind (mechanical energy) turns the
propeller, which then turns the electric generator, converting mechanical energy
into electrical energy.
• In a coal- or natural gas-powered electric generator, the chemical energy contained
in the coal or natural gas is converted into thermal energy, which moves the
turbine (mechanical energy), which turns the electric generator, creating electrical
energy. In a nuclear-powered electric generator, nuclear energy in the uranium
(rather than the chemical energy in coal or natural gas) is converted to thermal
energy.
Practice Questions
1.
The ability to do work or cause change is called
2.
The two main categories of energy are
energy (stored
energy (energy presently doing
energy) and
work or causing change).
3.
The form of energy that is found in large moving objects is
energy.
4.
The form of energy that is stored in large objects because of its position above
the ground is
5.
energy.
The form of energy that is stored in large objects because of its internal
condition, such as compression or tension, is called
energy.
6.
The form of energy stored in the bonds between atoms is
energy.
7.
The form of energy stored in the nucleus of atoms is
energy.
8.
Light and radio are examples of the
or
energy form.
9.
Moving electrons in a conductor are an example of
energy.
10.
Vibrating molecules and atoms are an example of
energy.
11.
The two kinds of nuclear reactions are
12.
In a roller coaster, both the kinetic and potential energy in the car decreases at
each successive hill because of
energy into
and
, which converts
energy.
13.
The energy transformation in the Sun is from
to
energy.
14.
The energy conversion that causes wind is from
energy in
to
energy in the
wind.
15.
The energy transformation in a flashlight is from
energy contained in the battery to
circuit, to
energy in the
and
energy
released by the light bulb.
16.
The energy transformation in photosynthesis is from
energy from
to
energy made by the chlorophyll in the plant.
17.
The energy transformation in cellular respiration is from
in the food that animals eat into the
motion and
energy of their
energy of their body heat.