Energy
Table of Contents
What Is Energy?
Forms of Energy
Energy Transformations and Conservation
Energy and Fossil Fuels
Energy
Learning Objectives
1. Describe how energy relates to work and power.
2. Describe kinetic energy and potential energy for
various real world examples.
Energy
Energy from Your Food (Calorimetry Lab)
Goal- Determine the amount of energy contained in a piece of food (a marshmallow).
Procedure:
1. Fill the soda can with 20 mL of water.
2. Measure the initial temperature of the water & the initial mass of the marshmallow (place the
pie plate, marshmallow, paper clip, and clay on the balance), then the Mr. Nye will light the
marshmallow about 1 inch underneath the soda can (held in place by you using tongs).
3. After the marshmallow is JUST finished burning, measure the final temperature of the water.
4. Then measure the final mass of the marshmallow. Again, place the pie plate, marshmallow,
paper clip, and clay on the balance to get the final mass of the marshmallow.
5. Determine the temperature change (final – initial) and the mass change (initial – final)
[both should be positive].
Data Analysis: Calculate the number of Calories per gram of marshmallow:
cal/g = (20 g Water x 1 cal/g*oC x Temperature change)/Change in mass
1000 calories = 1 Food Calorie
Food Calories per gram = (previous calculation)/1000
Theoretical Yield = 3.21 Food Calories/g
*Theoretical yield taken from the nutrition label (100 Food Cal/30 g).*
Energy
Calorimetry Lab Conclusions
Answer in the complete sentences…
1. How did your actual yield compare to the
theoretical yield of 3.21 Food Cal/gram?
2. What are some sources of error in this
experiment that would cause the actual
yield to be considerably less than the
theoretical yield? Hints: Does all of the
heat from the burning marshmallow go
directly into the water? If not, then where
does most of it go?
3. Keeping in mind that the grill lighter just got
the burning started, where did the energy
originally come from? How does this
experiment demonstrate the reason as to
why we need to eat food?
Energy
Learning Objectives
1. Describe how energy relates to work and power.
2. Describe kinetic energy and potential energy for
various real world examples.
Energy
Introduction to Kinetic & Potential Energy
Potential Energy is stored energy.
Examples: (Chemical) energy
stored in a battery or food, a
stretched rubber band (Elastic), or
a person or an object at a high
height (Gravitational)
Kinetic Energy is the energy of
movement or motion.
Examples: Any object or person
that is moving has a certain amount
of kinetic energy, Particles that
make up matter are constantly
moving.
Energy
Kinetic vs. Potential Energy Experiment
Goal: Determine the variables that affect the KE and PE for the go-car as it
goes down the ramp for 2 different masses.
Hypothesis: Predict how velocity will affect KE and how the height above
the ground will affect PE.
Background:
m = mass, v = velocity, g = acceleration due to gravity, h = height above the
ground
Kinetic Energy (KE) = Energy of motion = 1/2mv2
Gravitational Potential Energy (PE) = Stored energy = mgh
Energy
Machine
Setup
Mass Velocity
KE
Mass
m
v
1/2mv2
m
(kg)
(m/s)
(J)
(kg)
Gravity
g
(m/s/s)
Height
h
(m)
Top of Ramp
& no weights
0.25
0
0.25
9.8
0.5
Top of Ramp
& weights
0.50
0
0.50
9.8
0.5
Bottom of
Ramp & no
weights
0.25
From
your
data
0.25
9.8
0
Bottom of
Ramp &
weights
0.50
From
your
data
0.50
9.8
0
PE
mgh
(J)
Energy
Conclusions (in complete sentences)
1. State the relationships between the following
variables (use the equations for help too):
a) Velocity and KE
b) Height above the ground and Gravitational PE
2. Where on the ramp would the KE & PE be about
equal? Explain your answer with evidence from the
experiment. Hint- Where was there 0 KE but plenty
of PE and 0 PE but plenty of KE?
3. So, was any energy lost (outside of friction and
human error), or was the energy transformed from
one form to another (such as KE to PE or PE to
KE)? How was the energy transformed as the gocar went down the ramp?
Energy
Learning Objective
1. Describe kinetic energy and potential energy for
various real world examples.
Energy - What Is Energy?
Kinetic Energy
Kinetic energy increases as mass and velocity increases.
Energy - What Is Energy?
Potential Energy
Gravitational potential energy increases as weight and height
increase.
Energy - Energy Transformations and Conservation
Energy Transformations
Most forms of energy can be transformed into other forms.
Energy - Energy Transformations and Conservation
Transformations Between
Potential and Kinetic Energy
A pendulum continuously transforms energy from kinetic to
potential energy and back.
Energy
What’s the difference between kinetic and potential
energy?
A. Kinetic energy is stored energy while potential energy is
the energy of motion.
B. Kinetic energy deals with movement while potential
energy is stored energy.
C. They are the same type of energy (just different names).
D. I don’t know because I am not living up to my fullest
potential.
Energy
Which of the following would have the most kinetic
energy?
A.
B.
C.
D.
A person standing still on the ground.
A person standing on a cliff.
A bowling ball rolling at 2 m/s.
A ping pong ball bouncing at 2 m/s.
Energy
What happens to a car’s kinetic energy as it
decelerates to a stop at a red light?
A.
B.
C.
D.
The KE remains the same.
The KE increases.
The KE decreases.
The KE increases, then decreases.
Energy
Where on the diagram below would the ball have the
most kinetic energy?
A.
B.
C.
D.
Point A
Point B
Point C
None of the above
A
B
C
Energy
Which of the following describes what happens to a
basketball’s potential and kinetic energy as it falls
down through the basketball hoop to the ground?
A.
B.
C.
D.
The KE decreases while the PE increases.
The KE increases while the PE decreases.
The KE and PE both increase together.
The KE and PE both decrease together.
Energy
In which scenario would the skier have the most
potential energy?
A.
B.
C.
D.
A small skier at the top of a mountain.
A small skier at the bottom of a mountain.
A large skier at the top of a mountain.
A large skier at the bottom of a mountain
Energy
Which of the following best explains what happens
to potential energy and kinetic energy as a skier
goes down a mountain?
A. Kinetic energy is transformed into potential energy as the
skier goes down the mountain.
B. Potential energy is transformed into kinetic energy as the
skier goes down the mountain.
C. Potential energy and kinetic energy both increase as the
skier goes down the mountain.
D. Kinetic and potential energy remain the same.
Energy
Practice Test Answers
1- The person who passed you is your reference point, so you’ll feel like you’re going
slower.
2- velocity (speed and direction)
3- Walking then jogging & sled riding down a hill
4- Motion
5- Air resistance slows objects down in free fall.
6- Friction
7- Gravity causes objects to accelerate at 9.8 m/s/s towards the Earth.
8- House: greatest mass
9- Moving a golf ball at 2 m/s/s
Energy
Practice Test Answers
10- Car at 20 mph
11- lowering the applied force
12- Greater than 1
13- Wedge
14- lower than the output force or load weight
15- The smaller applied force is over a larger distance than the larger output force
(which is over a shorter distance)
16- Scissors, bike, car, human body, etc.
17- Slow the object down and/or lower its mass
18- Potential energy increases as kinetic decreases (as the snowball goes up higher);
then the Potential energy decreases as kinetic energy increases (as the snowball
goes down and increases in speed).
Energy
Practice Test Answers
19- Increase the distance (spread the objects farther apart) or lower the mass.
20- Straight slanted line going up and to the right or down and to the right.
21- Straight horizontal line going across
22- Find the slope (rise/run = change in distance/change in time)
23- Straight horizontal line; slanted line going down and to the right.
24- 1st and 2nd class levers lower the applied force; 1st class changes the
direction of the force too.
25- scissors, pliers, see-saw, crowbar
26- Wheelbarrow, bottle opener, door
Energy
Practice Test Answers
27- The applied force should be pointing up the ramp.
28- increase (M.A. = output force/input force)
29- Moving fast and trying to stop but end up still moving forward; trying to
move a heavy object from rest and it doesn’t move easily.
30- Rocket taking off- Fuel burns (downward force) which causes the
opposite reaction of the rocket moving upward; punching a wall- hit a wall
and the wall pushes back (possibly causing injury)
Energy - What Is Energy?
Using Prior Knowledge
Before you read, look at the section headings and visuals to
see what this section is about. Then write what you know
about energy in a graphic organizer like the one below. As
you read, write what you learn.
1.
2.
1.
2.
What You Know
The joule is the unit of work.
Energy has different forms.
What You Learned
Power is the rate at which energy is transferred.
The two basic kinds of energy are potential energy and kinetic
energy.
Energy - What Is Energy?
Links on Energy
Click the SciLinks button for links on energy.
Energy
End of Section:
What Is Energy?
Energy - Forms of Energy
Calculating Mechanical Energy
The kinetic energy of a 500-N
diver during a dive from a 10-m
platform was measured. These
data are shown in the graph.
Energy - Forms of Energy
Calculating Mechanical Energy
Reading Graphs:
According to the graph, how
much kinetic energy does the
diver have at 8 m?
About 1000 J
Energy - Forms of Energy
Calculating Mechanical Energy
Calculating:
Using the graph, find the
kinetic energy of the diver at 6
m. Then calculate the diver’s
potential energy at that point.
Kinetic energy = about 2000
J; potential energy = about
3000 J
Energy - Forms of Energy
Calculating Mechanical Energy
Inferring:
The mechanical energy of the
diver is the same at every
height. What is the
mechanical energy of the
diver?
About 5000 J
Energy - Forms of Energy
Building Vocabulary
After you read the section, reread the paragraphs that
contain definitions of Key Terms. Use the information you
have learned to write a definition of each Key Term in your
own words.
Key Terms:
Examples:
mechanical
nuclear
energy
energy
A type
The
form
of potential
of energyenergy
associated
calledwith
nuclear
the position
energyand
is
motion in
stored
ofthe
an object
nucleus
is of
called
an atom.
mechanical energy.
electromagnetic
thermal energy
energy
The sunlight
that you
eachenergy
day is of
a form
of
total potential
andsee
kinetic
the particles
in
electromagnetic
an object is calledenergy.
thermal energy.
electrical energy
The energy of electric charges is electrical energy.
chemical energy
Chemical energy is potential energy stored in the
chemical bonds that hold chemical compounds
together.
Energy - Forms of Energy
Links on Forms of Energy
Click the SciLinks button for links on forms of energy.
Energy
End of Section:
Forms of Energy
Energy - Energy Transformations and Conservation
Energy Transformations
Most forms of energy can be transformed into other forms.
Energy - Energy Transformations and Conservation
Transformations Between
Potential and Kinetic Energy
A pendulum continuously transforms energy from kinetic to
potential energy and back.
Energy
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Energy
Introduction to Chemistry
HindenburgHydrogen Gas
Explosion
Safety Protocol:
1. Do NOT touch anything on the back table until instructed to
do so.
2. Follow Lab Directions (if you are unsure, then ask).
3. Notify teacher of spills, broken or breaking glassware, and any
other problems.
Energy - Energy Transformations and Conservation
Energy Transformations Activity
Click the Active Art button to open a browser window and
access Active Art about energy transformations.
Energy - Energy Transformations and Conservation
Asking Questions
Before you read, preview the red headings. In a graphic
organizer like the one below, ask a question for each
heading. As you read, write answers to your questions.
Question
What is an energy
transformation?
Answer
An energy transformation is a
change from one form of energy
to another.
What are some examples of
transformations between
potential and kinetic energy?
Juggling and pendulums show
transformations between
potential and kinetic energy.
What is conservation of
energy?
The law of conservation of
energy states that energy
cannot be created or destroyed.
Energy
End of Section:
Energy
Transformations
and Conservation
Energy - Energy and Fossil Fuels
Use of Fossil Fuels
Fossil fuels can be burned to release the chemical energy
stored millions of years ago.
Energy - Energy and Fossil Fuels
Previewing Visuals
When you preview, you look ahead at the material to be
read. Preview Figure 18. Then write two questions that you
have about the diagram in a graphic organizer like the one
below. As you read, answer your questions.
Using Fossil Fuel Energy
Q. What energy transformation occurs in the sun?
A. Nuclear energy to thermal energy and electromagnetic energy
Q. What energy transformation takes place when coal is burned?
A. Chemical energy to thermal energy
Energy - Energy and Fossil Fuels
Links on Energy Transformations
Click the SciLinks button for links on energy transformations.
Energy - Energy and Fossil Fuels
Use of Fossil Fuels
Click the Video button to watch a movie about
the use of fossil fuels.
Energy
End of Section:
Energy and
Fossil Fuels
Energy
Graphic Organizer
Energy
exists as
Potential
energy
Kinetic
energy
measured in
is the ability
to do
Joules
Work
can be
Elastic
Gravitational
which at a
given rate is
Power
Energy
End of Section:
Graphic Organizer