The MAPs Team
Meaningful Applications Of Physical Sciences
Dr. Michael H. Suckley
Mr. Paul A. Klozik
Materials in this manual are based upon the Operation Physics program funded in part by the National
Science Foundation. All material in this book not specifically identified as being reprinted from another source
is protected by copyright. Permission, in writing, must be obtained from the publisher before any part of this
work may be reproduced in any form or by any means.
Participants registered for this workshop have permission to copy limited portions of these materials for their
own personal classroom use.
Energy
A. What Is Energy?
1. Does Energy (Light) Have Either Weight Or Volume? ------------------------- 8
2. What Makes It Move? ---------------------------------------------------------------- 9
2. Defining Energy? ---------------------------------------------------------------------- 10
3. How Is Energy / Work Measured? ------------------------------------------------- 12
4. How Is the Strength Energy Measured? (The Inverse Square Law) ----------- 13
B. Forms of Energy.
1. The Seven Forms Of Energy ---------------------------------------------------------- 16
2. Energy and the Human Body ------------------------------------------------------- 18
3. Transfer Of Chemical To Heat - Food Burning ----------------------------------- 23
4. Can Heat Make Things Move? ----------------------------------------------------- 24
5. Can Chemicals Make Things Move? ------------------------------------------------ 26
6. Using A Radio Speaker to Send Your Voice --------------------------------------- 29
7. Changing Mechanical Energy To Heat Energy ------------------------------------ 31
8. Energy Conversion Smorgasbord ---------------------------------------------------- 32
9. Energy Conversion Summary ------------------------------------------------------- 36
10. Energy Chains ------------------------------------------------------------------------ 38
C. Types of Energy.
1. Two types of Energy-Potential and Kinetic --------------------------------------- 40
2. Ah-La-Bounce ------------------------------------------------------------------------ 41
3. The weight of A Body and Its Gravitational Potential Energy ------------------- 44
4. Galilean Cannon ----------------------------------------------------------------------- 46
5. Another Way Of Storing Energy ---------------------------------------------------- 47
6. Investigating Potential / Kinetic Energy -------------------------------------------- 52
a. Does Potential / Kinetic Energy depend on Force?
b. Does Potential / Kinetic Energy depend on Mass?
D. Conservation of Energy (Energy cannot be Created Nor Destroyed “In Ordinary Circumstances”)
1. Is Energy Conserved When Converted to Work? --------------------------------- 57
a. Is Energy Conserved When Force is Changed?
b. Is Energy Conserved When Mass is Changed?
2. Energy Transformations and The Pendulum --------------------------------------- 59
3. Stop And Go Balls -------------------------------------------------------------------- 60
4. Coat Hanger Cannon ------------------------------------------------------------------ 63
5. Energy Transformations And The Hand Generator ------------------------------ 64
E. Work and Power
1. Determining Your Horsepower? ------------------------------------------------------ 70
2. Hot Rod Power ------------------------------------------------------------------------ 72
F. Energy Conversion Game ------------------------------------------------------------------ 73
Energy ©2004 ScienceScene
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WORKSHOP LEADER TOPIC INFORMATION
INTRODUCTION TO ENERGY
Energy is divided into four subtopics:
1. What is Energy?
2. Forms of energy and conversions
3. Types of Energy - Kinetic and Potential Energy.
4. Conservation of Energy.
The first subtopic examines the meaning of the term "energy," noting that energy is not a "thing," but rather a property that
objects can have. It begins with the idea that energy can make something move. The difference between force and energy is
discussed, work is defined and a more complete definition of energy as, "the ability to do work" is developed. These concepts
are reinforced by examining the energy input and output of the human body.
The second subtopic concerns some of the many forms of energy. In both demonstrations and lab activities, the students are
given many opportunities to reinforce the notion that energy is the ability to do work, that energy can be measured, and that
one form of energy can be transformed into another form of energy.
The third subtopic concerns potential energy and kinetic energy. Through a variety of activities the factors that affect
these kinds of energy are discovered, and for the upper levels the equations of gravitational potential energy and kinetic
energy are introduced
The last subtopic explores the concept of energy conservation. Through activities, demonstrations, and discussion, the
participants examine the idea that although energy can be transformed the total amount of energy remains the same. The
concept of why we could run out of energy even though it is conserved is also addressed. This is followed by a discussion of
mass-energy conservation, which is intended as an enrichment topic that can be presented with varying degrees of depth.
While the scope of this book is limited to the 'physics" of energy (which is often not discussed in many other popular
materials), it is recognized that the topic has many environmental, economic and social implications. The amount and the
forms of energy that we use are now seen to have a direct relationship to how we live our lives. The bibliography contains a
sample of some of the many resources that address these issues. Teachers are encouraged to use an interdisciplinary approach
to this topic to help their students reach an understanding of the relationship between energy and society.
Energy ©2004 ScienceScene
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WORKSHOP PLANNING MATRIX. - FNERGY
Idea
I. What is Energy?
A. Energy can make
things move.
B. Energy is the ability
to do work.
Name of
Activity
Type
Level
Duration
Lab
LA)
20-25 min.
Focus on Physics
Disc.
Defining Energy
How is Work
Lab
How Much Energy
Lab
Use in Climbing a Flight of Stairs?
Energy and the
Lab
Human Body
T
30 min.
L/U
L/U
30-45 min. Measured?
20-30 min. Do You
L/U
20-30 min. class time
24 hr. total time
Some Forms
of Energy
Demo
L/U
30 min.
Can Heat Energy
Make Things Move?
Can Chemicals
Make Things
Move?
1. Energy Chains
2. Energy
Transformations
3. Demonstrating
Lab
Lab
L/U
15 min.
Lab
L
25-30 min.
Lab
Lab
L/U
L/U
20 min. changed from
15-20 min.
1. Can you Change
Mechanical
Energy to Heat
Energy?
Demo/
Disc.
1.
1.
2.
3.
4.
II. There Are Many Forms of Energy,
A. Some forms of
1.
energy are: heat,
light (radiant),
sound, mechanical
2.
electrical and chemical.
.
3.
B. Energy can be
transformed
from one form
to another.
C. When energy is
changed from
one form to
another, often
some energy is
changed to
heat energy.
What Makes it
Move?
2. Can you
Change
Mechanical
Energy (motion)
to Heat Energy?
3. Heat Energy
L/U
30-40 min. Energy Transformations
T
20 min.
Lab
L/U
25 min.
Lab
L/U
45 min. Smorgasbord
Energy ©2004 ScienceScene
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III. Kinetic and Potential Energy,
A. A body may have
energy by virtue
of its position or
condition. This
type of energy is
called potential
or "stored up" energy.
1.
2.
3.
B.
A body may have
energy by virtue of
its motion. This type
of energy is called.
kinetic energy.
IV. Conservation of Energy
A. Energy can only
be transformed, the.
total amount of
energy remains the
same.
Focus On Physics:
Potential Energy
How Do Weight and
Height Affect
Gravitational Potential
Energy?
Another Way of
Energy
Demo
Disc.
T
25 min.
Lab
L/U
25-30 min.
Lab
L/U
30-45 min. Storing
1.
Focus On Physics:
Kinetic Energy
Disc.
T
30 min.
2.
Do Speed and Mass
Affect Kinetic Energy?
Lab
L
30-40 min.
1. Energy Transformations
Lab
L/U
30 min.
2. Stop and Go Balls
Demo. L/U
Disc.
Lab
L/U
15 min.
Disc.
T
15 min.
3.
4.
Energy
Transformation
Generator
What is Energy?
30 min. dons and the Hand
B. Even though the
total amount of
energy in the universe
is constant, it is not
always in a useful form
1. If the Amount of
Energy in the Universe
is Constant, Why Must
We Conserve It?
lab
L/U
30 min.
C. In special
situations, Like
nuclear reactions,
energy can be converted
to matter, and
matter into energy.
1. Focus on
Physics:
E=mc2
Disc.
T
20 Min.
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REFERENCES AND RESOURCES
Anderson, F.J. and Freier, G. D., A Demonstration Handbook for Physics, Stony Brook, N. Y.: American Association
of Physics Teachers. Second Makin
This publication has a wealth of simple demonstrations from all areas of physics and many that relate to the topic
of energy.
Enterprise for Education. Energy 80's, Santa Monica, CA: Enterprise for Education.
Check with your local utility company for this excellent collection of books loaded with ideas and demonstrations in
energy education. If the set is not available in your area. write to Enterprise of Education, 1320A Santa Monica Mall,
Suite 203, Santa Monica, CA 90401.
Hewitt, Paul. Conceptual Physics. Boston, Mass.: Little, Brown and Company, 5th Edition.
The chapter on energy and the section on heat are good background reading for the workshop presenters. Note in
particular, the home projects and exercises for these sections.
Lem, Tick L., Invitations to Science Inquiry. Lexington, Mass.: Ginn Press.
This. book should be in the library of all general science teachers. Many activities and demonstrations are
applicable to the topic of energy.
Oak Ridge Associated Universities. Science Activities in Energy, Oak Ridge Associated Universities, assisted by Lawrence
Hall of Science.
This is a series of pamphlets available through your local utility company. Illustrated cartoon style, each sheet of
activities can be copied and supplied to the students. Highly recommended.
Wilson, Mitchell and the editors of Life, Energy, New York Time, Inc
Part of the Life Science Library, this is an excellent resource for the historical development of energy concepts. Very
nicely illustrated and good background reading.
In addition to the references listed above, all of the many elementary-junior high science series produced by various
publishers contain projects, activities and demonstrations that the presenter might want to look over to expand the offerings
of the workshop.
Energy ©2004 ScienceScene
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WORKSHOP LEADER'S PLANNING GUIDE
WHAT IS ENERGY?
Idea A, "Energy can make things move" is a first look at the concept of energy. By investigating toys many questions are
raised, such as the difference between energy and force. This introductory activity is also an excellent opportunity for the
presenter to determine the students' initial level of understanding of the concept of energy.
Energy is defined in idea B, "Energy is the ability to do work." In this section some activities measuring work will be
performed and the units of measure for work and energy are discussed. The metric units used are consistent with current
elementary science programs. Activity "Energy and the Human Body" reinforces these concepts and demonstrates the
relevancy of energy in everyday life.
The only prerequisite for this topic is an understanding of the metric units of force and distance.
Naive Ideas:
1. The terms "energy" and "force" are interchangeable.
2. From the non-scientific point of view, "work" is synonymous with "labor." It is hard to convince someone that
more "work" is probably being done playing football for one hour than studying an hour for a quiz.
A.
ENERGY IS THE ABILITY TO MAKF THINGS MOVE.
1.
Activity: What Makes it Move?
This activity uses toys to begin to define energy and address the naive idea that "energy" and "force" are
interchangeable
B.
ENERGY IS THE ABILITY TO DO WORK.
1.
2.
3.
4.
Discussion - Focus On Physics: Defining Energy
Activity How is Work Measured? The pulling of an object up an incline is
used to define work and energy.
Activity: How Much Energy do you use in Climbing a Flight of Stairs?
The energy used to climb a flight of stairs is calculated in order to illustrate the joule as the unit of work and
energy.
Activity: Energy and the Human Body
An attempt to measure the energy input and output of a human body is made in order to show the relevancy of
energy in everyday life.
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DOES ENERGY HAVE WEIGHT OR TAKE UP SPACE?
Materials: Flashlight or desk lamp, Infant scale, bathroom scale, or lab balance. Measuring cup or graduated cylinder water,
Radiometer
PART I: Does energy (light) have weight?
1. Record the reading on the scale.
2.
Predict what will happen when you shine the flashlight on the scale.
3.
Observe the scale very carefully as you shine the flashlight. record the weight.
4. Experiment by varying the distance of the light from the scale (do not let the flashlight touch the scale!) Try
using a stronger source of light.
5.
From your experiment, what can you conclude about energy having weight?
6.
Can you think of any reasons why this experiment might not be a good method of determining whether or not energy
has weight?
PART II: Does energy (light) take up space?
1. Fill a measuring cup with water up to the 150 milliliter mark.
2. Shine the flashlight on the water for 5 minutes.
3. Observe the water level very carefully as you shine the light on the water. record any changes in the water
level.
4.
5.
Experiment by varying the length of time the light shines on the water. Try using a stronger source of light.
From your experiments, what can you conclude about energy taking up space?
6.
Why might this not be a very good experiment to determine whether or not energy takes up space?
Energy ©2004 ScienceScene
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WHAT MAKES IT MOVE?
Materials: Various types of toys that move such as: wind-up toys, cars. trucks, etc), battery operated toys (cars. trucks, etc),
air powered toys (balloons, rockets, etc) "gravity operated" toys (balls, yo-yo. etc.)
1. Operate (play with!) the toys at your lab station. Observe what they do. Describe what they have in common.
2. List each toy and describe what makes it move.
3. What would you call what makes all of these toys move?
Energy ©2004 ScienceScene
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WHAT MAKES IT MOVE?
IDEA:
Energy is the ability to do work.
If an object begins moving, then
being done on that object.
PROCESS SKILLS:
Observing
Communicating work is
LEVEL: TEACHER
DURATION: 20-25 min.
STUDENT BACKGROUND:
ADVANCE PREPARATION:
MANAGEMENT TIPS:
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
While this first activity does not require any background, it is an excellent
opportunity to determine the backgrounds of the students. Their responses
to the questions will indicate their level of understanding of what energy is
and may also identify many misconceptions about energy.
Collect an assortment of toys that move. This can be done by asking students to
bring in toys. asking friends with children to donate discarded toys, etc. If a toy
requires operating instructions, these can be written on cards that can be placed on
the tables with the toys. For example, an instruction to "Inflate the balloon (without
tying a knot) and release it," would be helpful to show it as a toy that moves.
The most important elements of this activity are allowing the students to observe and,
using the summary discussion, help them formalize what they have observed. It is
doubtful that many groups will just come up with the answers suggested below. A
more typical answer to, "What makes it move?" for the case of the wind up toy would
be "The spring." Follow-up questions by the instructor should lead them to what is in a
spring that makes it move. The discussion should offer the opportunity to address the
naive idea that the terms "energy" and "force" are interchangeable.
1.
2.
3.
They all move.
Chemical energy, elastic potential energy, etc.
Energy
1. Energy is the ability to do work. If an object begins moving, then work is being
done on that object A more complete definition of work is given in section IB.
2. Energy is not a thing, but rather a property that an object can have.
3. The terms "energy" and "force" are not interchangeable.
Continue this discussion by observing anything that moves. Discussion can be
stimulated by showing pictures of people running, moving cars, sailboats, etc.
Energy ©2004 ScienceScene
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FOCUS ON PHYSICS - DEFINING ENERGY
(Discussion)
1.
Discussion "Defining Energy"
Energy is a word like art, love or patriotism. You can think of lots of examples, but it is very difficult to come up with a
precise definition. We can get a handle on the problem, however, by defining it in terms of some-thing that can be
measured, work. Energy is the ability to do work. (This is an example of an operational definition).
The word work means different things to different people. When used in its scientific sense, it is defined as the product
of an applied force on an object and the distance the object moves in the direction of the force, that is:
Work = Force x Distance moved in the direction of the force, or: W = F x d
Forces can be measured with a spring scale in units called Newtons. Distances can be measured with a ruler in
meters. Once determining force and distance it is a simple matter to calculate the work that takes place in many
situations. The activity that occurs when work takes place is the result of the energy that is transferred from one body
to another in the process. The work done is numerically equal to the energy transferred.
2.
Discussion. "Work and Energy Units"
Most upper elementary science programs use the metric system of measurement for their examples and problems.
Forces are measured in Newtons and distances are measured in meters. The unit for work, then, is the Newton-meter
(F x d). The same unit can also be used for measuring energy.
Scientists decided to honor one of the early investigators of the concept of energy. Sir James Prescott Joule (18181889) by giving the Newton-meter a nickname, the joule.
1 Newton-meter = 1 joule
Work and energy, then, can be expressed in Newton-meters, or joules. Some other common units of work and energy
are:
kilowatt-hour (kwh) = 3,600,000 joules, used often to measure electrical energy.
calorie (cal) - 4.186 joules
kilocalorie (kcal) = 1000 calories = 4,186 joules. The Caloric used to measure the energy in foods should be
written with a capital "C" to indicate that it is really a kilocalorie or 1000 calories. Thus a 1 Calorie diet soft
drink is 1 kcal (1000 calories) and a 500 Calorie dessert is 500 kcal (500,000 calories).
An interesting activity is to have a student who travels overseas bring back a "Diet Coke" can from the country
they visit. In France, they say 1 kilocalorie, and in Australia, they say "Low Joule Cola?
Energy ©2004 ScienceScene
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HOW IS WORK and / or ENERGY MEASURED?
Materials: bricks, board, meter stick, spring scale (that reads in Newtons), object (roller skate or car), string
1. Using books or blocks make a ramp with the board as shown in the illustration above.
2. a) Measure the force necessary to pull your object at a constant speed on a flat surface.
____________Newtons
b) Measure the force necessary to pull your object at a constant speed up the ramp.
____________Newtons
c) Measure the force necessary to pull your object straight up (vertical) at a constant speed. ___________Newtons
3. Compare the results and explain ______________________________________________________________________
4. Measure the distance along the ramp, where the back wheels move as the skate is pulled from the bottom to the
top of the ramp. (i.e. measure the distance from the back wheels at the bottom of the ramp to the back wheels at
the top of the ramp.)
METERS ___________
5. Calculate the work done in pulling the object up the ramp.
WORK = FORCE x DISTANCE
______Joules
=
_______Newtons x ________meters
6. Calculate the work done in lifting the object the same distance vertically as it was previously raised by pulling it up the
ramp.
WORK = FORCE x DISTANCE
______Joules =
_______Newtons x ________meters
7. Compare the work done in pulling the object up the ramp to the work done lifting the object the same distance vertically.
Work done in pulling the object up the ramp. __________Joules
Work done in lifting the object vertically.
__________Joules
8. Explain why there is a difference in the values of Joules.
Energy ©2004 ScienceScene
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HOW IS WORK MEASURED?
IDEA:
Energy is the ability to do work.
PROCESS SKILLS:
Predict Compare
LEVEL: TEACHERS
STUDENT BACKGROUND:
DURATION: 30-45 min.
Students should be familiar with the metric system, and that
the Newton is the unit of force.
ADVANCE PREPARATION:
If this is to be a small group activity, you might ask several days before the scheduled
class for the students to bring in old roller skates and bricks. Other toys that have
relatively low friction wheels can be substituted for the roller skates, and other heavy
objects can be used instead of bricks. The idea is to keep the object to be pulled within
the range of the spring scale. (When measuring the total weight of the skate and brick,
each can be weighed separately and then add the two values added. Tie a string around
the brick to attach it to the spring scale.) An alternative to using boxes is to use plastic
film cans filled with sand (as used in IIA2). These can be placed inside the track that
the cars run in and the distances the cars move can be measured with the meter sticks.
MANAGEMENT TIPS:
Use caution handling bricks. This is not intended to be an exercise in how the inclined
plane is a simple machine, but rather an activity to illustrate how work and energy are
measured. The meter sticks should be placed just a little farther apart then the width of
the cars to ensure that the cars travel in a straight line.
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
4. (Work) joules = (Force) Newtons x (distance) meters.
7. It will probably not be obvious, but they should be the same. Discuss this with the
class, pointing out that in reality, pulling the skate and brick up the ramp may
require more work due to friction. See the book "SIMPLE MACHINES" for
more detail.
8. (Work) joules = (force) Newtons x (vertical distance) meters.
1. Only the force in the direction of the distance moved is used in calculating work.
2. The work done is numerically equal to the energy expended.
Energy ©2004 ScienceScene
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INVERSE SQUARE LAW
The intensity or strength of most types of energy (such as light, sound, gravity, electricity, and magnetism)
diminishes as we move away from the source. We have all seen the pattern created when a flashlight's beam spreads out as
it is moved further from a wall in a darkened room. The changing intensity of this pattern is described by the Inverse
Square Law.
The Inverse Square law indicates that the intensity (or the strength) of a magnetic field varies inversely with the
square of the distance from the magnet. This means that if the distance (d) increases, the intensity (I) decreases by the
square of the distance from the source (i.e. I is proportional to 1/d2 ).
Object
Strength = 1
One Distance Unit
Strength =
1
/4
Strength =
Two Distance Units
1
/9
Three Distance Units
You will use a laser for this investigation that is a brilliant laser designed to last and is the next generation in real optical
laser diodes so powerful it can be seen up to 1500 feet away! Designed in Germany and manufactured to the highest
quality standards. DO NOT point the laser beam into the eyes of humans or pets.
Experiment
1.
Place the “attachment” over the end of the laser. The “attachment is made from a piece of PVC pipe cut
approximately 2-5-cm long. This pipe has a piece of double diffraction grating glued on it.
2.
Hold the laser 1 meter as indicated in the table and shine on a flat surface. You will notice squares reflecting on the
surface. Select one of the squares and draw it on the surface.
3.
Hold the laser 2 meters from the surface. Align the same square with one side and bottom. Determine the number
of original squares it would take to fill the larger square.
4.
Hold the laser 3 meters from the surface. Align the same square with one side and bottom. Determine the number
of original squares it would take to fill the larger square.
5.
Compare the data and look for relationships.
Distance
Number of Squares
1-Meter
2-Meters
3-Meters
1
Distance Squared (D)
1/Distance2
∞ (Intensity)
Energy ©2004 ScienceScene
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WORKSHOP LEADER'S PLANNING GUIDE
THERE ARE MANY FORMS OF ENERGY
This subtopic is easy to present. and the workshop leader will have little difficulty eliciting the names of the various forms of
energy from the teacher's personal experiences. As each form is identified, it is shown to be a source of energy by its ability
to do work (sub topic 1, idea B). Several more demonstrations and activities are performed to show that energy can be
changed into heat. The ideas presented in subtopics I & II an the prerequisites for this subtopic.
Naive Ideas:
1. Things "use up" energy.
2. Energy is confined to some particular origin, such as what we get from food or what the electric company sells.
A. Some forms of energy are heat light (radiant) sound. Mechanical, electrical chemical ant) nuclear
1. Demonstration: Some Forms of Energy.
This demonstration uses a variety of objects to clarify the variety forms that energy lakes.
2. Activity: Can Heat Energy Make Things Move?
Certain types of candy wrappers and a light bulb are used to show that heat is a form of energy.
3. Activity: Can Chemical Energy Make Things Move?
Baking soda and vinegar are used to show that chemicals can contain energy.
B. Energy can re changed from one form to another.
1. Demonstration: Energy Chains. Everyday objects are used to trace energy
flow from one form to another.
2. Activity: Energy Transformations. A matrix is used to
illustrate energy transformations.
3. Activity: Demonstrating Energy Transformations Several different activities
with speakers illustrate energy transformations.
C. When energy is changed from one form to another often some energy is changed to heat energy.
1. Demonstration/Discussion: Can You Change Mechanical Energy to Heat Energy? Three different
ways to demonstrate the transformation from mechanical energy to heat.
2. Activity: Can You Change Mechanical Energy (motion) to Heat Energy? Shaking sand in styrofoam containers
illustrates the transformation from kinetic energy to heat energy.
3. Activity: Heat Energy Smorgasbord. This activity contains five short labs showing heat energy resulting
from energy transformations.
Energy ©2004 ScienceScene
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SOME FORMS OF ENERGY
(Demonstration)
Energy was defined as the ability to do work. If an object begins moving, then work is being done on it, and therefore, some
form of energy is being used. We refer back to this idea to demonstrate some of the many forms that energy can take. It is
suggested that a list of energy forms be generated by the students. Examples of each form can be taken individually and
demonstrated to show its ability to make something move. As each is shown, the objects are placed on a table with a card
labeling that form of energy. For example if a student mentions coal, a demonstration of how chemical energy causes motion
can be shown. If another student mentions gasoline the instructor can point out that it is another form of chemical energy.
The objective of this demonstration is to make similarities and differences between the many forms of energy "come alive"
to focus discussion. It is not intended as an attempt to classify every form of energy in the universe. Some suggestions arc as
follows:
1.
Heat: Heat a bimetallic strip with a match or candle flame. Ask "Does heat make things move? Is heat a form of
energy?"
Another example of heat to motion that might be used is the form of the pin wheel found in Christmas ornaments that
makes use of the convention currents from candles to produce rotation, or a "palm glass" that uses heat from a person's
hand to partially evaporate a colored liquid causing the remaining liquid to be forced up a glass tube..
2.
Light: Start a radiometer moving with a flashlight. If a flash attachment from a camera is available, try "kick" starting
the radiometer with the flash. For each of the forms of energy, ask:
Does _____________ make things move?
Is ________________ a form of energy?
3.
Sound: A sound apparatus that consists of a tin can, a balloon and a small mirror that will demonstrate that sound can
cause something to move. Another example would be to use two matched tuning forks (preferably mounted on
sounding boxes). Striking one fork will cause the sound from it to set the other one in motion.
4.
Mechanical: This type of energy is the kinetic and potential energy of objects. There are a variety of toys that can be
used here to demonstrate mechanical energy.
5.
Electrical: Hold up the plug to an electric fan and ask "What form of energy are we dealing with here?" (Electric).
Plug in the fan and turn it on. As an alternative. use a battery operated toy. Show the battery first and ask the same
question as you would with the plug. Insert the battery and make the toy move. (If a battery
is used, then it is stored chemical energy, not electrical energy).
6.
Chemical: Half fill a test tube with vinegar. Put about Sec (or about half a teaspoon) of baking soda into a rubber
balloon. Attach the end of the balloon to the top of the test tube and shake the baking soda into the vinegar. The gas
produced (CO2) will make the balloon expand (Stretching the balloon first by blowing it up and releasing the air will
make this more dramatic.) A variation of this example is to place a few drops of water into the bottom of a plastic
35mm film can and drop in an "Alka-seltzer" tablet and quickly snap on the lid. Place the can on the table in such a
way that the lid will not hit anyone when it pops off.
7.
Nuclear: Use a Krieger counter in listen to background radiation. Hold the Geiger tube near a piece of ordinary rock and
note that the background activity remains the same. Now hold the tube near a radioactive sample. Now the sharp increase
in activity, both) by the speaker and the deflection of the meter needle. This may seem kind of far-fetched, but it does
make an impression on the viewers that indeed, nuclear energy does make things move.
Energy ©2004 ScienceScene
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SEVEN FORMS OF ENERGY
1. Heat
2. Light
3. Sound
4. Mechanical
5. Electrical
6. Chemical
7. Nuclear
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ENERGY AND THE HUMAN BODY
Materials: chart, "Calories Burned Per Hour", chart, "Calorie Content in Common Foods" log sheets
Energy is used in the human body to do work internally as well as externally. Internally, energy is used for all of the many
processes that keep us alive such as respiration, circulation, digestion, etc. Externally, energy is what allows us to do work on
our body as a whole such as in climbing up stairs, or to do work on other objects such as when throwing a baseball. The body
gets its energy from food (chemical energy see p 23). The purpose of this activity is to become acquainted with energy and its
units by attempting to measure energy that is put into your body in a day and comparing it to what is used. This activity
simplifies some of the calculations that must be made to regulate your body's food intake for health regulations and is not
intended for use as a nutrition guide. For more complete information consult a Registered Dietician.
1.
Using the log sheets supplied below, keep track of everything you eat in a 24 hour period. Beside each type of food
list the number of Calories it contained by referring to the chart "Calorie content in common foods" (page 20-21).
2.
On the same log sheets record each and every activity you do and note for how long you do it. Beside each activity list
the amount of calories used up in the activity by referring to the chart "Calories burned per hour" (page 19). If the
activity you did is not listed, pick the calories burned from an activity that you think requires about the same amount of
energy. (Note: The numbers on this chart include both the external energy to do the activity and the internal energy to
keep a person alive.)
3.
What was the total number of Calories you took in during this period?
4.
Convert this amount of energy from Calorie units to joules, remembering that a Caloric used by dieticians is really
a kilocalorie which is 4,186 joules.
___________ Calories
_____________ calories x 4186 joules per calorie = ____________ joules
5.
Calculate your weight in Newtons (one pound is approximately 4.5 Newtons)
Weight in pounds x 4.5 Newtons per pound =____________________Newtons
6.
The energy calculated in 4 is the amount of work this food can do. If all of this work went into climbing a mountain,
calculate how high you could go. (Note: since Work = Force x Distance; Distance = Work/Force. The force required
to pick yourself up is your weight)
Distance = Work / Force
_______ meters = _______ joules / ________Newtons
7.
Compare the height you calculated to the height of Mt. Everest which is approximately 8850m. Do you think you
could really climb this high using the food energy you ate during a 24 hour period? For what else must your food
energy be used?
8.
According to the estimates on your log sheets, what was the total number of Calories you used during this 24 hour
period?
___________________ Calories
9.
How does the amount of energy you put into your body during this period (step #3) compare to the estimate of the
amount that you used? If there is a difference, what do you think this will cause?
10. A net gain or loss of 7700 Calories from your diet represents a gain or loss of 1 kilogram of body mass (or about 2.2
pounds of weight). Did you gain or lose mass during this period? If so, calculate how much.
Energy ©2004 ScienceScene
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CALORIES BURNED PER HOUR
ACTIVITY
50
Backpacking
Basketball
Canoeing
Climbing
Crew
Cycling (Leisure)
(Racing)
Dancing (Slow)
(Fast)
Fishing
Gardening (Mowing)
(Digging)
Golfing
Gymnastics
Horseback riding
Ironing
Judo/Karate
Mopping
Painting
Playing Piano
Running (10 min/mile)
(9 min/mile)
(8 min/mile)
(7 min/mile)
(6 min/mile)
(5 min/mile)
Shopping
Sitting
Skating (Ice)
(Roller)
Sking (Moderate)
(Maximum)
Skin Diving
Sleeping
Swimming (Slow)
(Fast)
Tennis
Typing
Volleyball (6 person)
Walking
Weight Training
400
415
130
360
310
240
510
155
310
185
355
375
260
280
200
100
585
185
135
120
360
580
650
730
835
870
185
65
255
270
330
540
620
60
385
470
335
85
185
240
560
60
470
485
155
420
365
265
600
180
365
220
395
445
300
315
235
115
690
220
185
145
450
685
750
835
935
1025
220
70
295
305
375
730
730
65
455
550
385
95
225
285
665
(Body mass in kilograms)
70
75
85
540
565
180
485
420
305
690
210
420
255
455
515
350
360
270
130
795
250
220
165
530
785
850
936
1035
1180
250
85
345
355
430
850
840
80
520
635
445
110
260
325
755
Energy ©2004 ScienceScene
600
635
205
550
475
365
780
235
475
290
515
580
390
405
305
150
900
285
245
190
600
895
960
1040
1145
1335
285
95
385
400
480
1005
955
90
595
720
505
125
295
360
850
690
715
230
620
535
420
870
265
535
320
575
650
440
455
340
170
1005
320
280
210
650
995
1060
1145
1245
1490
320
110
435
445
545
1105
1060
100
660
805
565
140
320
395
955
100
770
800
260
710
600
480
980
295
600
365
655
730
500
515
390
190
1145
365
305
240
730
1135
1200
1285
1385
1695
365
125
485
510
620
1260
1210
110
750
920
645
155
355
450
1085
Page
19
ENERGY CALORIE CONTENT IN COMMON FOODS
MEAT
Bacon
2 slices
Beans, Refried
1/2 cup
Beef, Ground
3 oz.
Beef, Roast
3 oz.
Beef Liver
3 oz.
Bologna
slice
Chicken, Fried
leg and thigh
Egg, Fried
large
Egg, Hard-Boiled
large
Egg-Scrambled
large
Frankfurter
2 oz
Ham, Baked
3oz
Meat Loaf
3 oz.
Peanut Butter
2 tbsp
Peanuts
1/4 cup
Peas, Blackeye
12 cup. dried
Perch, Fried, Breaded
3 oz
Pork Chop
3 oz.
Sausage
2 pork links
T-Bone Steak
3 1/3 oz.
Tuna
3oz
135
Cheese, Cheddar
slice
Cheese, Cottage
12 cup
Cheese, Monterey
slice
Cheese, Mozzarella
(pan skim) slice
Cheese Spread
1 oz.
Cheese, Swiss
slice
Cocoa
3/4 cup
Ice Cream, Vanilla
12 cup
Ice Milk, Vanilla
1/2 cup, soft serve
Milk
1 cup
Milk, Chocolate
I cup
Milk, Lowfat 2%
1 cup
Milk, Lowfat 1%
I cup
Milk, Skim
1 cup
Milkshake, Chocolate
10.6 oz.
Pudding, Chocolate
1/2 cup
Yogurt, Plain
1 cup
Yogurt, Strawberry
1cup
Yogurt, Vanilla
1cup
212
GRAIN
168
Bagel
Biscuit
enriched
Bread, Rye
slice
Bread, W bite
slice, enriched
Bread, Whole Wheat
slice
92
142
186
18 2
195
86
201
83
79
95
172
179
230
- 186
211
94
193
308
MILK
Buttermilk
1cup
Cheese, American
99
106
114
109
1 06
Energy ©2004 ScienceScene
106
82
107
164
135
112
150
208
121
102
86
356
161
Cornbread
2 1/2"x3". enriched
Cornflakes
3/4 cup
Crackers, Saltines
5
Hominy Grits
1/2 cup, enriched
Macaroni
1/2 cup, enriched
Noodles, Egg
12 cup, enriched
Oatmeal
1/2 cup
Pancake
4' diameter, enriched
Raisin Bran
1 cup, enriched
Rice
12 cup
Roll, Frankfurter
enriched
Roll, Hamburger
enriched
Roll, Hard
enriched
Toast, White
slice
Tortilla, Corn
6". enriched
Waffles
2. enriched
191
72
60
62
78
100
66
61
144
112
119
119
156
61
63
130
144
FRUIT • VEGETABLE
255
194
165
103
61
61
55
Apple
medium
Banana
medium
Beans, Green
12 cup
Broccoli
12 cup
Cantaloupe
1/4 medium
Carrot Sticks
5" carrot
Coleslaw
12 cup
80
101
16
20
29
21
82
Page
20
CALORIE CONTENT IN COMMON FOODS
Corn
1/2 cup
Grapefruit, Pink
1/2 medium
Orange
medium
Orange Juice
1/2 cup
Peaches
1/2 cup
Pear
medium
Peas, Green
1/2 cup
Potato, Baked
Large
Potatoes, French-Fried
20 pieces
Potatoes, Mashed
12 cup
Raisins
412 tbsp
Tomato
1/2 medium
Tossed Salad
3/4 cup
Watermelon
1 cup
70
48
65
56
100
101
54
132
233
63
123
22
COMBINATION FOODS
13
Bake Beans with Pork 156
1/2 cup
Beef Potpie
1/4 of 9" pie
Beef & Vegetable Stew
1 cup
Chicken Chow Mien
1 cup
Chili Con Carne
with Beans
1 cup
Lasagna
2 1/2" x 4 1/2"
Macaroni and Cheese
1/2 cup
Pizza, Cheese
1/4 of 14" pie
Soup, Chicken Noodle
cup
Soup, Tomato
I cup
Spaghetti w/Meal Bails
1 cup
Taco, Beef
52
OTHERS
Butter or margarine
I tsp
Cake, chocolate
1/16 of 9" cake
Cake, Sponge
1/12 of 10" cake
Candy Bar, Chocolate
I oz.
Chocolate Syrup
2 tbsp
Coffee, Black
3/4 cup
Cookie, Sugar
3" diameter
Doughnut, Cake Type
French Dressing
1 tbsp
Gelatin
1/2 cup
Gravy, Beef
1/4 cup
Jelly, Currant
1 tbsp
Maple Syrup
1 tbsp
Mayonnaise
1 tbsp
Pie, Apple
1/6 of 9" pie
Popcorn, Unbuttered
1 cup
Potato Chips
10 chips
Roll, Danish Pastry
Sherbert, Orange
1/2 cup
Soft Drink, Cola
1 cup
Sugar
1 tsp
36
234
196
147
93
2
89
125
66
31
FAST FOODS
49
Burger King's
Whopper
Dairy Queen's
Brazier Dog
Kentucky Fried Chicken's
Original Recipe Dinner
McDonald's Big Mac
McDonald's
Cheeseburger
McDonald's
Egg McMuffin
McDonald's
Filet-0 Fish
Pizza Hut's
Supreme Pizza
3 slices
Taco Bell's
Bean Burrito
50
101
403
23
114
274
135
96
14
670
280
643
563
307
327
432
5 10
343
388
209
255
333
633
215
354
59
173
332
216
71
Energy ©2004 ScienceScene
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21
ENERGY AND THE HUMAN BODY
IDEA:
Energy is important in everyday life.
PROCESS SKILLS:
Measuring Interpreting Data
LEVEL: Teacher notes
DURATION: 24 hr
20-30 min. (class time)
STUDENT BACKGROUND:
The complete activity requires that students are familiar with work and how it is
measured. If students lack this background, eliminate numbers 4-7 of the activity.
ADVANCE PREPARATION:
introduce the activity and pass out log sheets, "Calorie Burned per Hour" chart
and "Calorie Content in Common Food" chart early enough to allow the students
the 24 hours required to collect the data. Students may need extra copies of the log
sheets and may need to be shown how to calculate the Calories for an activity that
is not an even number of hours. (e.g. 400 Calories burned per hour x 1.25 hours =
500 Calories.)
MANAGEMENT TIPS:
It is important to remember that the purpose of this activity is to become
acquainted with energy and its units by looking at how the human body uses
energy. This activity simplifies some of the calculations and does not consider that
good nutrition is much more than merely a matter of calories. Therefore, it is
important to emphasize the activity is not accurate enough to use for health
reasons and is not intended as a nutrition guide. For more complete information
consult a Registered Dietitian.
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
4. If the person ate 2500 Calories:
2500 Calories x 4146 joule per Calorie = 10,465,000 joules
5. If the person weighed 150 pounds: 150 pounds x 4.5 Newtons
per pound = 675 Newtons
6. Using a 675 Newton (150 lb) person who eats 10,465,010 joules (2500
Calories):
15,504 meters . 10,465.000 joules / 675 Newtons
7. No. Much of the energy used must go into internal energy.
9. I used less (or more) energy than I took in. This will cause me to gain (or
lose) mass.
10. If a person used 1000 Calories less than he or she took in then the gain in
mass would be:
1000 Calories/ 7700 Calories per kilogram = .13 kg (.13 kg
on earth weighs about .29 lb)
A large amount of energy we use is required for internal life processes. The
amount varies from person to person depending on a variety of factors, which is
one of the reasons that the numbers used in "Calories Burned Per Hours" chart
are only rough estimates. Typically only about 15-30% of the energy input is
used for voluntary muscular activity.
1. It is an interesting activity to try to use the "Calories Burned Per Hour" chart
to plan a day that would use exactly the amount of calories ingested.
Remember to include all of the activities in a 24 hour period since this is the
amount of time you kept track of your food intake.
2. A similar activity could be devised using the energy input and output of an
automobile.
Energy ©2004 ScienceScene
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TRANSFORMATION OF CHEMICAL ENERGY TO HEAT ENERGY
Problem: How do we determine the number of calories present in food?
25 ml. Water
Pin
Aluminum Foil Covered Cardboard
1. Obtain one half of a peanut, determine its mass (m) in grams, and place the peanut on the pin in the cork.
2. Fill the test tube with 25.0 ml. of water. Record its mass (Mwater) and temperature (T1).
(25.0 ml of water has a mass of 25.0 grams).
3. Light the peanut with a match, and place the test tube over the flame.
4. When the peanut finishes burning, record the temperature of the water (T 2). Calculate the change in temperature (∆T) by
subtracting T1 from T2.
∆T = T2 – T1
5. Assuming all the energy in the peanut was transferred to the water, calculate the number of calories in the peanut by
multiplying the mass of the water by the temperature change. H = M water x ∆T
6. Determine the number of food Calories in the peanut by dividing the number of calories by one thousand.
7. Repeat the process for a different food sample, and record the data in the space provided.
DATA TABLE
Sample A - Peanut
Sample B -
1. mass of material (g)
2. mass cold water (Mwater)
3. Temp. cold water (T1)
4. Temp. heated water (T2)
5. Temp. chg. of water (∆T)
6. calories (H)
6. calories
Energy ©2004 ScienceScene
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CAN HEAT ENERGY MAKE THINGS MOVE?
Materials: chewing gum wrapper (foil/paper combination) scissors, source of heat (incandescent light bulb) and socket
1. Cut a strip from the wrapper .5 centimeters wide and 6 centimeters long.
2. Hold the strip, slimy side down, over the glowing bulb. Observe what happens.
3. Describe what happened to the strip.
4. Explain how this demonstrates that heat is a form of energy.
5. Predict what will happen if the strip is removed from the source of heat and placed in a cool spot near a window or in a
refrigerator.
6. Check your prediction in Step 5 by moving the strip from a source of heat to a much cooler area.
7. Experiment by using a piece of paper the same dimensions as the strip cut from the wrapper.
Does the heat from the bulb make the paper move? _____________
Try a strip cut from aluminum foil. Does the heat from the bulb make the foil move? __________________________
8. Explain why the gum wrapper was a better detector of heat than the paper or aluminum foil.
Energy ©2004 ScienceScene
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CAN HEAT ENERGY MAKE THINGS MOVE?
IDEA:
To show that heat energy is truly a form
Predicting Inferring
PROCESS SKILLS:
Observing
LEVEL: TEACHER
STUDENT BACKGROUND:
DURATION: 15 min.
Students should know that energy makes things move.
ADVANCE PREPARATION:
The type of wrapper paper needed is-the kind that has a thin layer of
aluminum bonded to paper. This type of wrapper can also be found on
"Hershey's" miniature chocolate bars. Several snips can be cut from each
wrapper.
MANAGEMENT TIPS:
Have the students use caution with the scissors, as well as with the hot bulb.
RESPONSES TO
SOME QUESTIONS:
3.
4.
5.
7.
8.
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
The snip bends away from the light bulb.
Energy makes things move. Energy is the ability to do work. The heat
from the bulb does work on the strip.
It straightens out.
No, No.
The aluminum side of the paper expands more than the paper side,
causing it to bend.
1. Energy makes things move.
2. The heat from the lamp did work on the snip, causing it to bend.
Bimetallic strips used in thermostats are dial-type thermometers.
Energy ©2004 ScienceScene
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25
CAN CHEMICAL ENERGY MAKE THINGS MOVE?
Objectives:
1. Collect measurement data for class discussion using the Alka-Poppers.
2. Identify the conversion of chemical energy to mechanical energy.
Introduction:
An Alka-Poppers is made by placing water and part of an Alka-Seltzer tablet in a film container and then placing on the
cap. The gas given off by the Alka-Seltzer builds up enough pressure to pop the cap.
Materials: 1 film container, 10 ml graduated cylinder, clock with second hand, 1 package of Alka-Seltzer tablets,
thermometer, triple beam balance, English/ metric measuring device
Procedure: (Work with one or at most two partners)
1. Open your packet of Alka-Seltzer tablets and determines the mass (weight) of one tablet. Carefully break each tablet
into four pieces. Determine the mass (weight) of one of the 1/4 tablet pieces.
2.
Record the temperature of the water.
3.
Place 1/4 of an Alka-Seltzer tablet into the film container with 8.0 ml. of water and immediately place the lid on the
container. Note: Replace the Alka-Seltzer when there is no longer enough gas to make the cap pop.
4.
Record the temperature of the water after the explosion and calculate the change in temperature due to the explosion.
5.
Obtain the average distance the cap goes using three trials. (Try to get the greatest distance)
6.
Obtain the time to pop the cap for three trials and determine the average.
7.
Using 1/2 of an Alka-Seltzer tablet estimate the number of explosions that would occur in one minute then actually
perform the experiment.
Data:
¼ tablet
1. (1)
2. (2,4)
½ tablet
¾ tablet
Mass
Temperature
1
3. (5)
2
Distance:
3
Av.
5. (6)
1
2
Time to explode
3
Av.
6. (7)
Number of explosions
Conclusion: (summarize what you have done and what you have learned concerning this activity)
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
Energy ©2004 ScienceScene
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CAN CHEMICAL ENERGY MAKE THINGS MOVE? - Alternate
Materials: soda bottle, small balloon, piece of string, vinegar, baking soda, graduated cylinder balance
1.
Measure 60 milliliters of vinegar and pour into the soda bottle.
2.
Measure out 7 grams of baking soda and place it into the balloon.
3.
Put the neck of the balloon over the top of the bottle, being careful not to let the baking soda fall into the vinegar.
4.
Tie a string around the necks of the balloon and the bottle to keep the balloon from "popping off."
5.
Raise the balloon to allow the baking soda to fall into the vinegar.
6.
Observe what happens as the baking soda mixes with the vinegar.
7.
Describe what happened
8.
Explain how this experiment demonstrates that chemicals are a source of energy.
Energy ©2004 ScienceScene
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CAN CHEMICAL ENERGY MAKE THINGS MOVE?
IDEA:
To show that chemical energy is truly
a form of energy
PROCESS SKILLS:
Observing
Inferring
LEVEL: TEACHER
DURATION: 25-30 min.
STUDENT BACKGROUND:
Students should know that energy makes things move.
ADVANCE PREPARATION:
All of the materials are easy to gather. The amount of vinegar and baking
soda can be estimated if graduated cylinders and balances are unavailable.
MANAGEMENT TIPS:
Pre-stretching the balloon by blowing it up and releasing the air will make
it easier for the gas from the reaction to inflate the balloon.
RESPONSES TO
SOME QUEST1ONS:
POINTS TO EMPHASIZE 1N
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
7. The mixture starts to bubble and the balloon inflates.
8. Mechanical reaction produces a gas (carbon dioxide). The gas does
work on the walls of the balloon.
1. Energy makes things move.
2. The gas produced as a result of the chemical reaction did work on the
balloon.
The expanding gases in an automobile engine as a result of the
explosions in the cylinders.
Energy ©2004 ScienceScene
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USING A RADIO SPEAKER TO SEND YOUR VOICE
-
Materials: 2 radio speakers, 2 30 cm lengths of stranded wire with alligator clips on each end, 1 galvanometer, 1
flashlight battery (1.5 volts, any size), 5 meters of #I8 lamp cord (alligator clips on each end)
1.
Use the alligator clips to connect the two wires to the two tabs on one of the radio speakers. Hold the clip
on the other end of one of the wires, to either end of the flashlight battery. Tape the end of the second
wire on to the other end of the battery. Observe the speaker.
2.
Describe what happened.
3.
Identify the energy transformations that took place.
4.
Return the battery to the teacher and obtain a galvanometer. A galvanometer is a very sensitive meter that
will indicate a tiny electric current by the motion of its needle. Connect the loose ends of the two wires on
the speaker to the two terminals on galvanometer.
5.
Very acidly touch the center of the paper cone of the speaker. Press it very lightly several times. Observe
the meter.
6.
Describe what happened.
7.
Identify the energy transformations that wok place.
8.
Experiment by shouting into the radio speaker and observing the galvanometer. Identify the energy
transformations that took place.
9.
Connect a speaker to each end of the long piece of lamp cord. If possible, try to have one of the speakers in the next
room or in the corridor with the door closed as much as possible without breaking the wire.
10. Hold one of the speakers up close to your ear as a classmate talks into the other speaker. The person doing the
talking may have to cup their hands around the speaker to funnel the sound directly onto the cone. Repeat the
procedure except this time, you talk into the speaker while the other person listens.
11. Identify the links of the energy chain related to this experiment
Energy ©2004 ScienceScene
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USING A RADIO SPEAKER TO SEND YOUR VOICE
IDEA:
Energy can be changed from one form
to another.
LEVEL: TEACHER
STUDENT BACKGROUND:
ADVANCE PREPARATION:
MANAGEMENT TIPS:
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
PROCESS SKILLS:
Classifying
Experimenting
DURATION: 30-40 min.
Students should be familiar with the different forms of energy and know that
energy can be changed from one form to another.
Several weeks before this activity, have the students bring in old or discarded
radios from home. Very carefully remove the speakers trying not to puncture
the paper cones. Miniature speakers can also be purchased for several dollars
from an electronics store, such as Radio Shack.
Caution the students not to press too hard on the paper cones or to puncture
them by improper handling.
2. The speaker "clicks" each time the wire is tapped on the battery.
3. Electrical- mechanical - sound.
6. The needle on the meter moves back and forth when the cone is pressed
7. Mechanical - electrical (to mechanical once again as the needle
moves).
8. Sound - mechanical - electrical - mechanical.
11. Sound - mechanical - electrical - mechanical - sound.
1. Mechanical energy can be changed to electrical energy.
2.
3.
POSSIBLE EXTENSIONS:
Electrical energy can be changed to mechanical energy and sound.
Sound energy can be changed to mechanical energy, which can be
changed to electrical energy, which can be changed back to mechanical
energy and back to sound.
Discussion of how microphones work.
Experimenting with string telephones (two cans connected by a string).
Energy ©2004 ScienceScene
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CAN YOU CHANGE MECHANICAL ENERGY
TO HEAT ENERGY?
(Demonstration/Discussion)
Drop a ball and watch as the bounces get progressively smaller. What is happening to the energy of the ball?
Where does it go?
Pound a block of wood with a hammer several times.
What happened to the kinetic energy of the hammer as it struck the wood?
To answer these questions, we must look at one of the most prevalent forms of energy, heat energy.
What is commonly called heat energy is related to the several kinds of internal energies that the molecules of a substance
may have. One type of internal energy that molecules can have is kinetic energy. A thermometer is a device that allows us
to measure the average kinetic energy of the molecules of a body, and thus, its temperature. For a given object, the higher
the temperature the more heat energy it contains.
In the case of the bouncing ball, some of the energy was lost as sound, and some was lost in the form of heat energy. Both the
molecules of the ball and the molecules in the floor had their kinetic energy increased upon impact, thus raising the
temperature a tiny amount. This is also true of the hammer pounding on wood.
Some demonstrations illustrating the transformation of mechanical energy to heat energy are as follows:
a. Pound a nail into a block of wood and pull it out. Feel the nail. Its hot.
b. Drill a hole into a piece of hard wood such as oak or maple. The drill bit and the shavings get hot, (Be careful! The
drill bit can get very hot)
c. Beat upon a piece of hard wood with a hammer and very quickly place a sheet of temp erature sensitive liquid crystal
material over the spot. Note the color change indicating a rise in temperature. (Relatively inexpensive thermometers
made of liquid crystal are available in drug stores and will work with this demonstration.)
d. Materials: 2 styrofoam cups strong tape, thermometer fine dry sand
1. Fill one cup about 1/3 full of sand.
2. Very carefully. insert the bulb of the thermometer into the sand, wait about two minutes and record the reading
on the thermometer.
__________degrees
3. Remove the thermometer, invert the second cup over the first, and seal well by wrapping the tape around the
seam between the two cups. Vigorously shake the sand back and forth inside the cups. Continue shaking for
five minutes, passing the bottle among the members of your group.
4. After the five minutes are up. carefully punch a hole in the top of the container and insert the thermometer into
the sand. Record the temperature.
__________degrees
5. Compare the two temperature readings. Record the difference in temperature.
__________degrees
6. Explain what you had to do to the bottle of sand to raise its temperature.
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CAN YOU CHANGE MECHANICAL ENERGY
(MOTION) TO HEAT ENERGY?
IDEA:
When energy is changed from one form to
another, in most cases, some energy is
changed to heal
PROCESS SKILLS:
Measuring
Experimenting
LEVEL: TEACHER NOTES
STUDENT BACKGROUND:
DURATION: 25 min.
Students should be familiar with the forms of energy, and understand that
energy can change from one form to another.
ADVANCE PREPARATION:
Check on sources of sand, such as pet shops (aquarium sand), the heath,
etc.
MANAGEMENT TIPS:
Make sure cups are tightly fastened. Have the students use care when
inserting the thermometer into the sand.
RESPONSES TO
SOME QUESTIONS:
4. The temperature should be higher.
6. The student had to do work on the sand to raise its temperature.
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSS1ON:
1. Mechanical energy can be transformed to heat energy.
2. Work had to be done on the sand to raise its temperature.
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ENERGY SMORGASBORD
Materials: elastic bands, hand drills, nails, block of wood, hammer, pieces of coat hangers, cap for 3/4 copper tubing,
superball, modeling clay, thermometers
Arranged around the room, you will find stations, each one having the materials to demonstrate the transformation of
mechanical energy to heat energy. Try the experiment at each station, recording your results on this paper.
STATION #1: ELASTIC RANDS
1. Touch one of the elastic bands to your upper lip, sensing its temperature.
2. Remove the elastic from the vicinity of your lip, expand it rapidly, and while still stretched, once again touch it to your
upper lip. Describe the sensation on your lip.
3. Was work required to stretch the elastic band?
4. Identify the energy transformations that took place.
STATION #2. HAMMER NAIL AND BLOCK OF WOOD
1. Hold a nail to sense its temperature, and then carefully pound the nail about 4 to 5 centimeters into the block of
wood. Identify the work required to do this.
2. Using the claw part of the hammer, pull the nail out of the wood. Immediately touch the part of the nail that was stuck
in the wood. Describe the sensation.
3. Identify the energy transformations that took place.
STATION #3. SUPERBALL
1. Very carefully place the bulb of the thermometer into the hole drilled in the. ball. Record
the temperature. _______________ degrees. Remove the thermometer from the ball.
2. Bounce the ball against a hard surface for about 5 minutes. Take turns with the other members of your group.
3. After 5 minutes, insert the bulb of the thermometer into the drilled hole. Record the temperature. ______ degrees.
4. Identify the energy transformations that took place.
STATION #4. COAT HANGER WIRE PIECES
1. Measure one milliliter of water into a small test tube. Secure the temperature of the water. __________degrees.
2. Bend the coat hanger wire back and forth rapidly until it breaks in the middle. Quickly place the two broken ends into
the water in the test tube. Once again, record the temperature of the water. degrees.
3. Describe the work done on the piece of wire.
4. Identify the energy transformations that took place.
STATION #5: COPPER CLIP
1. Farm a base around the small copper cup using the modeling clay. Bring the clay up to the edge of the copper cup.
2. Measure out two milliliters of water into the copper cup. Record the temperature of the water. _________ degrees.
3. Secure the nail into the chuck of the hand drill with the head of the nail sticking out.
4. Position the head of the nail against the bottom of the cup and turn the handle on the drill for 5 minutes. Do this
without stopping, taking turns with the other members of your group.
5. After 5 minutes, record the temperature of the water. ________ degrees.
6. Describe the work you did on the drill.
7. Identify the energy transformations that took place.
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ENERGY SMORGASBORD
Device
Type
1. Radiometer
Demo
2. Festaware and Geiger counter
Demo
3. Shaking solids I – Copper/steel
Demo
4. Shaking solids II - Plastic
Demo
5. Shaking solids III - Sand
Demo
6. Wintergreen Mint and pliers
Act
7. Battery
Act
8. Battery and Bulb
Act
9. Battery and motor
Act
10. Motor and Bulb
Act
11. Alka Poppers
Act
12. Hand Generator
FYI
13. Radio speaker and Galvanometer
Demo
14. Radio speaker to radio speaker
Demo
15. Hammer nail and Wood
FYI
16. Rubber bands
Act
17. Balloon and Lip
Act
18. Superball and thermometer
Act
19. Coat hanger, test tube, water
Act
20. Talking strip
FYI
21. Photo cell
Demo
22. Matches
FYI
23. Picture
FYI
24. Piezoelectric crystal and Neon bulb
FYI
25. Clap on clap off
Act
26. Nerf Ball Cannon
Demo
27. Toy car
Demo
28. Bimetallic Strip
FYI
29. Thermocouple and Galvanometer
Demo
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ENERGY SMORGASBORD
IDEA:
When energy is changed from one form
to another. in most cases, some energy
is changed to heat.
PROCESS SKILLS:
Observing
Measuring
LEVEL: TEACHER NOTES
DURATION: 45 min.
STUDENT BACKGROUND:
Students should know the forms of energy, and that energy can be changed from one
farm to another.
ADVANCE PREPARATION:
Start early gathering the materials for this activity. Practically all are readily available,
and things like superball might be supplied by the students. Check around for a hand
drill. The high school shop teacher might be willing to loan one.
MANAGEMENT TIPS:
The teacher will have to use caution in this activity because pieces of coat hanger wire
have sharp ends, elastic bands might be sent flying and fingers could he mashed while
hammering nails. For health reasons, the elastic band should be discarded after a student
places it on his or her lips.
RESPONSES TO
SOME QUESTIONS:
STATION #1
The band feels warm when it is stretched.
2. Yes, a force was exerted through a distance.
3. Chemical (muscular) - kinetic - elastic potential - heat energy.
STATION #2
1. The force of the hammer times distance drive the nail into the wood.
2. The nail feels warm.
3. Chemical (muscular) - gravitational potential - kinetic - heat energy.
STATION #3:
1. The temperature should he higher.
4. Chemical (muscular) - kinetic - gravitational potential - elastic potential - heat energy.
STATION #4:
3. The force to bend it times distance it was bent.
4. Chemical (muscular) - kinetic - gravitational potential - elastic potential - heat energy
STATION #5:
5. The temperature should be higher.
6. Hand exerted a force through distance while turning the crank.
7. Chemical (muscular) - kinetic - heat energy.
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION: When energy is changed from one form to another, in most cases, some energy
is changed to heat.
POSSIBLE EXTENSIONS:
1.
Paper clips can be bent back and forth and then placed on the lips to detect an
increase in temperature, in a manner similar to the one used in station #1. (Be sure
to discard the paper clip after each use, and be careful of any sharp edges.)
2.
Thermometers made of a sheet of liquid crystals are available in drug stores, and can
be used to illustrate the increase in temperature of the nail.
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ENERGY CONVERSIONS
How can one form of energy be converted to another form of energy?
In the chart write the name of a device that converts the form of energy listed along the left of the chart to the form
of energy listed along the top of the chart. For example: the conversion of light energy to mechanical occurs using a
device called the Radiometer.
Light
Light
Mechanical
Heat
Sound
Electrical
Chemical
Radiometer
Mechanical
Heat
Sound
SonoLuminescence
Electrical
Chemical
1. Describe all steps in an energy chain beginning with the sun and ending with a light bulb.
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ENERGY CONVERSIONS
IDEA:
Energy can be changed from one form
to another.
PROCESS SKILLS:
Inferring
Classifying
LEVEL: TEACHER NOTES
DURATION: 15-20 min.
STUDENT BACKGROUND:
ADVANCE PREPARATION:
MANAGEMENT TIPS:
RESPONSES TO
SOME QUESTIONS:
Familiarity with the variety forms of energy.
It is not necessary to fill in every box. The purpose of this activity is to
stimulate thought and discussion about energy transformation.
Light: light bulb, sound: thunder, mechanical: steam/auto engine, electrical:
thermo-couple, chemical: strike a match
Light - heat solar collector, mechanical: radiometer, electrical:
solar cell, chemical: photosynthesis
Sound - mechanical: microphone
Mechanical (Motion - heat friction, sound: radio speaker. electrical:
generator
Electrical - heat stove, light lightning, sound: radio speaker, mechanical:
electric motor, chemical: battery charger
Chemical - heat burning, light Lumastick and fire flies, mechanical:
dynamite, electrical: battery
Nuclear - heat atomic bomb reaction, light atomic bomb, sound: atomic
bomb, mechanical: atomic bomb, electrical: nuclear power plant
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ENERGY CHAINS
An energy chain is a picture or drawing of a series of energy transformations which traces the movement of energy from its
origin to a specific outcome or activity.
Where does the energy come from, needed for a monkey to move?
Energy Chain:
Sun → Photosynthesis → Banana → Monkey → Chemical Energy → Mechanical Energy (Monkey Moves)
Where does the energy come from that is needed for a fisherman to fish?
Energy Chain:
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ENERGY CHAINS
IDEA:
Energy can convert from one form to another.
A series of energy conversions can be called an
energy chain.
PROCESS SKILLS:
Observing
Inferring
LEVEL: TEACHER
DURATION: 45 min.
STUDENT BACKGROUND:
ADVANCE PREPARATION:
MANAGEMENT TIPS:
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
Students should be able to recognize a form of energy.
In the previous section, each of the forms of energy were shown to have the
ability to make something move. Although it was not specifically mentioned,
the participants were also witnessing a series of energy conversions from the
form under consideration to mechanical energy. In this demonstration a series
of energy conversions, or "energy chains' will be demonstrated. Have the
participants identify the energy forms involved as each change takes place.
Each chain can be ultimately traced back to our main source of energy, the
sun.
Some suggested "energy chains" am as follows:
a. Wind-up toy (starting with the sun: nuclear - radiant - heat chemical - mechanical - sound - heat)
b. Battery operated toy (starting with the time it is turned on:
chemical - electrical - mechanical - sound - heat)
c. Lumastick (chemical - light)
d. Match (after being struck chemical - heat - light)
e. Hand generator (starling with the sun: nuclear - radiant heat - chemical - mechanical - electrical - heat - light sound)
It is often helpful to group similar devices at the same work stations to show
the connections between them. For example, a rubber ball that can be
bounced could be placed with a small pendulum.
The responses will depend on the devices. In many cases the energy can be
traced back to the sun. For example the energy to pick up a ball can be traced
to food (chemical) which can be traced back through the food chain to solar
energy.
It is important to emphasize that things do not use up" energy. but rather the
energy changes form. For example. in a battery operated toy, energy transfers
from being concentrated in the chemical energy of the battery. through several
forms, until it ends up as heat energy scattered around the room. in its final
form it is less useful because it isn't concentrated, but it is not "used up."
(More derail on this idea is presented in section IV.)
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WORKSHOP LEADER'S PLANNING GUIDE
THERE ARE TWO TYPES OF ENERGY
Using several activities, the participants will get some "hands on" experiences illustrating examples of potential and kinetic
energy. For the upper level grades (6-8). the equations for gravitational potential energy and kinetic energy will be discussed.
The only prerequisite for this subtopic is an understanding of the metric units of force, mass, and distance.
Naive Ideas:
1. An object at rest has no energy.
2. The only type of potential energy is gravitational.
3. Gravitational potential energy depends only on the height of an object.
4. Doubling the speed of a moving object doubles the kinetic energy.
A. A body may have energy by virtue of its position or condition. This type of energy is called potential or "stored up"
energy.
1. Demonstration/Discussion - Focus On Physics: Potential Energy.
2. Activity: How Do Weight and Height Affect Gravitational Potential Energy?
3. Activity: Another Way of Storing Energy.
B. A body may have energy by virtue of its motion this type of energy is called kinetic energy.
1. Demonstration/Discussion - Focus On Physic's: Kinetic Energy.
2. Activity: Does Speed and Mass Affect Kinetic Energy?
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FOCUS ON PHYSICS - POTENTIAL ENERGY
(Demonstration/Discussion)
Materials: hammer (should be lying on a desk or table) block of wood, nails, elastic band, wind-up toy, two identical
magnets
Begin by saying "Energy is the ability to do work With respect to the top of the desk, can this hammer do work? Does it
have the ability to make things move?" (No) Raise the hammer a short distance above the top of the desk, and ask, "How
about now?" (Yes). Under the raised hammer, place a block of wood with a nail partially imbedded in it. Let the hammer
drop, further driving the nail into the wood. Have the participants identify the force applied, the distance through which the
force acted and the work done. Since the hammer had the ability to do work when it was raised, then it must of had energy
in it when it was in this position. Energy stored in an object because of its position is called potential energy. Note too, that
work had to be done in lifting the hammer, an amount of work equal to the potential energy gained by the hammer.
Hold the large elastic band in the palm of your hand. Ask "Does this elastic band have potential energy with respect to the
palm of my hand?" (No). Stretch the elastic and hold it in the stretched position. Ask "Does it have potential energy now?"
(Yes). "Why?" (There was a change in the condition of the long spiral molecules that make up rubber compounds as they
were pulled into a stretched position. Once again. note that work had to be done to increase the potential energy of the band.
The potential energy gained is equal to the work done in stretching the band). Set an unwound mechanical toy on the desk
and ask the same type questions. "Does it have potential energy with respect to the top of the table?" Wind it up. "Does it
have energy now?" Release it so the students can see it move. Identify the work done to increase the potential energy of the
wind-up toy. "What part of the toy had its position or condition changed as the winding took place?" (The spring). This type
of stored energy is called elastic potential energy.
Place a magnet on the desk and ask the same type of questions. "Does it have potential energy with respect to the top of the
table?" Take another similar magnet and push it against the first one so that their like poles are held together. "Does it have
energy now?" Release it so the students can see it move. Identify the work done to increase the potential energy of the
magnets. The magnets gained energy because of their position. This type of stored energy is called magnetic potential
energy.
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1. Potential or stored energy
PE = F x h
2. Kinetic or moving energy
KE = ½m x v2
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AH-LA-BOUNCE
Purpose: To discover the amount of potential energy a super ball has before and after one bounce. To calculate
the amount of energy absorbed in the bounce.
Equipment: super ball, measuring tape, calculator
Procedure:
1. Stretch as high as possible and mark a spot on the wall. This will be the initial height, and the height you will drop the
super ball. Record the height (h1) from the top of the ball in meters
2.
Drop the ball so that you get a good (straight up) bounce.
3.
Mark the maximum height of the first bounce. Record the height (h 2 ) from the
top of the ball in meters.
h1
4.
Make at least three trials and average the height (h 2)
5.
Find the mass of the ball, record as mass (m) in kilograms.
6.
Using the constant for the acceleration due to gravity (g) as 9.8 m/sec2.
7.
Calculate PE1 = m x g x h1 in the unit joules.
8.
Calculate PE2 = m x g x h2 in the unit joules.
h2
(Estimate the amount of energy absorbed. )
9.
Calculate the % of energy absorbed. % of energy absorbed = ((PE 1 - PE2) / PE1) x 100.
absorbed is the amount of energy that was used up in the bouncing of the ball.
The % of energy
DATA TABLE
Mass of super ball ______________Kg
Mass of tennis ball ______________Kg
Super Ball
Tennis Ball
Trials
h1 (meters)
h2 (meters)
h1 (meters)
h2 (meters)
1
2
3
average
Potential Energy
m x g x h
% of energy absorbed
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HOW DO WEIGHT AND HEIGHT AFFECT GRAVITATIONAL
POTENTIAL ENERGY?
Materials: Aluminum pie plate (disposable type), 2 film cans (one filled with sand), meter stick, spring scale (0-5 Newtons),
2-30 cm pieces of string
I. Gravitational potential energy and height
1. Place pie plate upside down on the floor.
2. Place the film cans (empty and full) on the pie plate. Can the pie plate support them without being dented?
3. Remove the film can from the pie plate. Lift the empty film can to a height of .25 m above the plate. Drop the can
onto the plate. Describe what it did to the pie plate.
4. Predict what will happen if the empty can is dropped from a height of 1 m.
5. Drop the empty can from a height of one meter. Did your predictions come true? (You may repeat the dropping from
both heights several times to check your results. Flatten out any dents between drops.) Explain how the height of an
object affects its potential energy.
II. Gravitational potential energy and weight
6. Tie a string around each film can so they can be hung on the spring scale. Weigh each can.
mass of empty can _______________ mass of full can ____________________
7. Predict what will happen if each can is dropped onto a pie plate from a height of 0.5 m.
8. Drop each can from a height of .5 in starting with the empty can. Repeat this several times, flattening out the plate
each time. Explain how the weight of an object affects its gravitational potential energy.
III. Energy In everyday life
9. Why would a sledgehammer be used to split rocks rather than a carpenter's hammer?
10. People in the upholstery business use a small hammer called a tack hammer. Would you want to build a house with
only a tack hammer for nailing? Explain.
11.. Would be falling off of the bottom step of a ladder or the top step be more dangerous,? Explain you answer using
potential energy.
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HOW DO WEIGHT AND HEIGHT AFFECT GRAVITATIONAL
POTENTIAL ENERGY?
IDEA:
A body may have energy by virtue of its position or
condition. This type of energy is called potential or
"stored up" energy. One form of potential energy is
gravitational potential energy. The more weight or
height an object has, the more gravitational potential
energy is stored in it.
PROCESS SKILLS:
Inferring
Observing
LEVEL: TEACHER
DURATION: 20-25 min.
STUDENT BACKGROUND:
At this point, students should know that energy is the ability
to do work.
ADVANCE PREPARATION:
If spring scales are at a minimum, one can be shared by all of the
groups. Pennies or (almost) any heavy small objects may be used
as a substitute for the sand in the film cans.
MANAGEMENT TIPS:
1. Students may want to open the filled film can to see what's
inside. Caution them to do this with care and to seal it back
up securely to avoid spilling the contents.
2. An alternative to using the pie plate is to drop the
objects into modeling clay or play dough. Then a
permanent record of the impacts can be kept
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
2 Yes.
3. The pie plate is slightly dented.
5. Yes. The more height an object has the more
gravitational potential energy is stored in it.
7. The empty plate will be dented more by the full can than
by the empty can.
8. The more weight an object has the more gravitational
potential energy is stored in it at a given height.
9. A sledgehammer is heavier than a carpenter's hammer.
therefore at a given height it will have more energy.
1. Relate the size of the dent to the amount of work done on
the pie plate. The larger the dent the more work done, and
therefore the film can had more gravitational potential
energy .
2. The potential energy gained by a body is equal to the work
done on it (computed by multiplying), the force exerted
(equal to the weight of the body) times the vertical distance it
is raised (height). Gravitational potential energy, then, is
simply equal to the weight of a body times the height to
which it is raised.
PEgrav = weight x height = Newtons x meters = joules
POSSIBLE EXTENSIONS:
Try to relate this to examples of potential energy in your
geographic areas such as avalanches, hydroelectric power,
water towers, putting hay in a loft, etc.
Energy ©2004 ScienceScene
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GALILEAN CANNON
A.K. Dewdney
A rubber ball bounces handily on a hard floor, but nothing bounces like a steel ball on a firmly supported steel plate.
There is a strange device (see the Reading List). I call the Galilean cannon that exploits the astonishing elasticity of steel to
create some equally astonishing speeds. No gunpowder is necessary for a Galilean cannon, just a few cannonballs of different
sizes!
When two elastic bodies such as balls collide, there is a transfer of momentum between the bodies. For example, a
moving ball may strike an identical stationary ball squarely in the center. The moving ball will instantly stop and the
stationary ball will move off at the same speed of the original ball. If the
moving ball is very much larger than the stationary one, it will continue
on nearly unabated and the smaller ball will rocket off at twice the large
balls velocity.
This, at least, is the theoretical picture. In the real world, this
collision is less than 100% efficient, the stationary ball moves off at a
slightly slower speed, and so on. But I will pretend, in describing the
Galilean cannon, that we live in an ideal world in which inconvenient
details can be ignored.
Only in the idealized laboratory of the mind are many inventions
and ideas first tried out. Those of you who build the Galilean cannon will
discover the truth for yourselves.
Imagine the following experiment. If a steel ball is dropped on a
steel plate, the ball will rebound to the point at which it was dropped.
Suppose that a large steel ball is dropped on the steel plate and that
almost immediately a second, smaller ball is released directly above it.
Within a millisecond of the large balls bounce, the second ball collides
with it.
In a Galilean Cannon, a ball falls (left) and rebounds
(right)
If the large ball had reached a velocity of v when it struck the plate, it will rebound upward with this same speed. The
second ball, according to Galileo, is also traveling at the speed v when it strikes the large ball going upward (neglecting the
large balls diameter for the moment).
What happens when a large ball collides head-on with a small ball, both traveling at the same speed? If the large ball is
sufficiently massive, it will lose practically no speed in the collision and the small ball will rebound at a speed of 3v. Think
about this for a moment.
In this simple mental experiment lies the seed of an idea for a cannon of sorts. Imagine, for example, three steel balls,
one 10 centimeters (4 inches)in diameter, one 2 centimeters (0.8 inch) in diameter and one about the size of a ball bearing,
say 4 millimeters (0.16 inch). The three balls are dropped as a train, each directly over its predecessor, as shown in Figure 3.
There does not need to be any space between the balls. The rebounds will occur anyway.
What happens when the three-ball train hits the steel plate? The bottom ball will rebound at speed v and, as we have
already seen, the second ball will rebound at speed 3v. How fast will the third ball rebound? It is time to solve the general
problem.
If a heavy ball is moving upward at speed v when it strikes a light ball moving downward at speed y, imagine a frame of
reference that moves upward with the larger ball. Relative to this frame, the small ball approaches at a speed of x + y. It
therefore rebounds from the larger ball at a speed of x + y in the upward direction. But that is in relation to a frame of
reference that is already moving upward at speed x. This speed must therefore be added to the speed of the upward rebound,
x + y, resulting in the speed 2x .+ y. Now, if x is 3v and y is v, the answer to the question just posed is 7v!
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As some readers may already have begun to suspect, each time we add a new ball to the train, the speed doubles, in
effect. Here is a little table showing rebound velocities for trains of up to eight balls:
Number of
Balls
1
2
3
4
5
6
7
8
Rebound
Speed
1v
3v
7v
15v
31v
63v
127v
255v
To really appreciate the idea in more concrete terms, imagine that the eight ball train is dropped from a height of 10
meters (33 feet). This is about the roof height of a two-story house. The velocity of the train when it hits a massive steel plate
or block on the ground would be slightly greater than 10 meters per second, but we will suppose just 10 meters per second for
ease of calculation. On the rebound, the smallest ball whizzes upward at 2,550 meters (8,364 feet) per second. This is more
than twice the speed of a high-velocity rifle bullet and more than seven times the speed of sound. Galilean cannon balls may
not be large, but they are fast!
One might imagine putting a ball bearing in orbit with a Galilean cannon by adding just a few more balls.
Unfortunately, air friction would intervene. And so would a lot of other factors, in any case.
Those of you with a little physics background are in an excellent position to calculate what the rebound velocities would
be for actual steel balls. Taking both the coefficient of restitution of a steel ball, as well as actual masses into account will
produce more modest velocity formulas (but not that modest). The effect is still very much there even when each ball in the
train is twice the diameter of its successor. This brings us to actual construction.
In an experimental Galilean cannon, the "ball§' are not necessarily spherical. Solid steel rods with rounded ends might
work as well. In such a case, greater lengths would have larger masses. The last two or three "balls' might be truly that, each
nestled temporarily in a little pocket in its predecessor. The whole train could then be dropped down a smooth steel pipe, the
barrel of the Galilean cannon.
Caution: Needless to say, anyone who builds this device with the hope of exploring its technological limits must take
appropriate safety precautions when testing it. In particular, arrange to drop the balls remotely from a safe location and either
use a deflector plate to contain the shots or take due care that the balls do not land where there are likely to be people!
ABOUT THE AUTHOR
A,K. Dewdney, who for eight years wrote columns about computers and mathematical recreations for Scientific American,
is a professor of computer science at the University of Western Ontario, He is the rounding editor of Algorithm, a magazine
devoted to recreational and educational computer programming. Professor Dewdney's interests extend far beyond the realm
of computing to include amateur astronomy, paleontology, botany and biology,
Energy ©2004 ScienceScene
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ANOTHER WAY OF STORING ENERGY
Materials:
1.
empty thread spool, Q-tips, or large wooden matches, elastic bands, paper clip, scotch tape, button
Loop the rubber band through two of the holes in the button as shown.
2.
Make a small hook in the end of a paper clip and use it to pull the rubber band through the hole in the spool, as
shown below.
3.
Hold the rubber band in place in the spool by inserting a short length of Q-tip or a piece of the wooden match
through the ends of the band. Use small pieces of rape to hold the stick in place, as shown below.
4.
Insert a Q-tip or match through the other end of the rubber band, so that one end sticks out beyond the edge of the
spool, as shown below.
5.
Using the long end of the stick, wind the rubber band 5 complete turns. Place it on its side on a table and let it go.
Observe the result.
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6.
Explain what happened to the spool when it was placed on the table.
7.
Why did you have to wind the elastic band?
8.
Explain where the energy came from to drive the spool.
9.
Wind the spool again 5 times and using a ruler, measure how far it travels. __________ Centimeters
10. Predict what will happen if you wind the rubber band 10 turns. Test your prediction by winding the band 10 times and
letting it go on the table. Describe the result and compare it to your prediction.
11. Experiment with your motorized spool by measuring the distance it travels when it is wound 10, 15, 20 turns.
10 turns ______ centimeters
15 turns ______ centimeters
20 turns
centimeters
Does the spool go twice as far with 20 turns as it did with 10 turns? Explain why it did or did not.
12. Wind the rubber band 10 turns and hold the stick in place with a piece of tape. Put the spool away until the next
day.
13. After storing the spool oversight, remove the tape and release the spool on the table. How far does the spool go
now?
__________ Centimeters
14. How well did the rubber band store energy overnight?
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ANOTHER WAY OF STORING ENERGY
IDEA:
PROCESS SKILLS:
A body may have energy by virtue of its position or
condition. This type of energy is called potential or
"stored" energy.
Observing
Inferring
LEVEL: TEACHER
DURATION: 30-45 min.
STUDENT BACKGROUND:
Students should have discussed the meaning of potential energy. Also,
work must be done to store energy in a spring or elastic band.
ADVANCE PREPARATION:
Stan early rounding up spools. Ask the children to bring in spools from home.
Tailor shops and fabric stores may have spools they would be willing to donate.
Plastic spools can be used, however the paper ends should be kept on. The rest of
the materials are readily available.
MANAGEMENT TIPS:
The students enjoy assembling this rubber band motor. Caution the students not
to hook themselves with the bent paper clip. Experiment with the number of turns
of the stick. Too many alms result in wild and erratic motion. If there is too much
friction try lubricating the surface between the button and the spool by rubbing
them with an old candle.
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
6.
7.
8.
10.
11.
It was driven along by the elastic as it unwound.
To do work (store energy) by changing the tension in the band.
The potential energy stored in the rubber band.
It travels farther. More work done, more potential energy.
Part 2: Probably not. Energy lost as driving stick skids on the table top
(friction).
14. Very well.
Work must be done in storing energy in the elastic band. Have the students
identify the force and the distance.
Doing twice as much work may not give you twice as much useful energy. The
tighter the elastic band is wound, the faster the stick spins, causing a greater
amount of slippage on the table.
POSSIBLE EXTENSIONS:
1. Large versions of this motor can be made with spools used by photo
developing shops to hold photographic paper, and pencils instead of matches.
2. Rubber band motors in model airplanes.
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FOCUS ON PHYSICS
KINETIC ENERGY
(Discussion)
When a person throws a bowling ball, work is done on the ball to get it going. Once the ball is going it has the ability to do
work on another object such as the pins at the end of the lane. This "energy of motion" is called kinetic energy.
Kinetic energy is very important in everyday life. A car traveling down the mad has kinetic energy, and the more it has the
harder it is to stop. Moving water was used to run mill wheels in the old days and is used today to ran hydroelectric power
plants. This water has energy because it is moving — kinetic energy. It is the kinetic energy of the wind that is used to make
wind generators and sailboats go. Sometimes, such as in tornados and hurricanes, the kinetic energy of the wind becomes too
much and can cause great destruction.
Kinetic energy is also important on the microscopic scale. The more kinetic energy the molecules of an object have, the
hotter it will be. Heat energy is related to kinetic energy. The sounds people hear are caused by the motion of their ear drum.
Sound is also related to kinetic energy!
The next activity investigates the factors that affect the kinetic energy of an object.
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INVESTIGATING POTENTIAL AND KINETIC ENERGY
Objectives
1. Given the following list of terms, identify each term's correct definition. Conversely, given definitions identify their
correct terms. acceleration, force, kinetic energy, mass, Newton, potential energy, power, velocity,
2. Given the formula for potential energy P.E. = m x g x h, or the formula for Kinetic Energy K.E. = 1/2 m x v2,
determine which formula to use and calculate the amount of energy.
3. Given the formula for work w = f x d, calculate the amount of work given force and distance.
4. Given the formula where p = power, w = work, and t = time calculate the power using the formula p = w / t.
5. Identify the affect of force on potential and kinetic energy.
6. Identify the affect of mass on potential and kinetic energy.
Materials
toy truck
2 - .060 Kg masses
string for mass
device to change height of inclined plane
Meter stick
inclined plane - ramp
Newton scale
mass to be pushed
stopwatch with sensors
.0355 Kg mass
balance or pre-massed objects
Truck Set-Up
1. Set-up the equipment as indicated in the figure.
a. connect the two pieces of the ramp together.
b. connect the electronic sensor to the stopwatch
c. place one of the sensors in the t1 position and the other sensor in the t2 position. The distance is 0.400-m.
d. adjust the height of the support block to the height indicated in the table.
e. place the support block at the .380-m position.
.380-m
Finish – t2
Start - t1
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Section 1: Does Potential And Kinetic Energy Depend On Height (Force)?
While keeping the release position constant we will vary the force (height)
1. In this experiment we will keep the release position
Variables
Small Truck
constant while varying the height of the support block. This
will change the force on the truck.
Truck Height (h)
Measure & Record
Force on truck (f):
Measure & Record
2. Determine and record the mass of the truck.
Mass
of
truck
(m):
Measure & Record
3. Set the block, as indicated in the table, and place the block
Timed
Distance
(d):
0.40-m
under starting point of the truck. Measure and record the
Position
from
Start:
0.38-m
truck height (h) from the top of the table to the top of the
Independent
Variable
ramp, at the starting point.
Block Height: 1
0.03-m
4. Measure the force of the truck using the Newton scale.
Block
Height:
2
0.06-m
Hook the Newton scale on the truck and hold the body of
Block
Height:
3
0.09-m
the scale in your hand parallel to the ramp so the weight of
the scale does not pull on the truck.
5. Release the truck and measure the time needed to travel through the timed distance.
6. Repeat the experiment changing the support block height. Remember to measure the height and the force for each new
support block height.
7. Calculate the average time, velocity, potential and kinetic energy. Formulas are provided in the chart.
8. Does the change in height (force) on the truck effect time and energy, explain?
9.
Explain why potential energy and kinetic energy are not numerically equal.
Position from Start:
Mass of truck (m)
-m
Height (h): Measured
-Kg
Timed Distance (d):
Gravity (g): 9.8 m/sec2
-m
Block Height: Given
Time Trials
Experiment
Block
Height
(meters)
Height of
Truck (h)
(meters)
Force on
Truck
(Newton)
Trial
1
(seconds)
Trial
2
(seconds)
Trial
3
(seconds)
Speed
Average
Time
(seconds)
V=d/t
(m / sec)
Energy
Potential
P.E.=
mgh
(Joules)
Kinetic
K.E.= ½
mv2
(Joules)
1
2
3
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Section 2: Does Potential And Kinetic Energy Depend On Mass?
While keeping the starting point and height constant we will vary the mass.
1. Set-up the equipment as indicated. In this experiment we will
keep the support block position and starting position constant
while varying the mass the truck.
2. Set the block, as indicated in the table, and place the block
under starting point of the truck. Measure and record the truck
height (h) from the top of the table to the top of the ramp, at
the starting point.
3. Place the indicated mass on the truck and determine the mass
of the truck and load. Measure the force of the truck and load
using the Newton scale.
4. Measure the time taken to travel the timed distance.
Variables
Truck Height (h):
Force on truck (f):
Position from Start:
Timed Distance (d):
Block Height:
Independent Variable
Mass of truck (m): 1
Mass of truck (m): 2
Mass of truck (m): 3
Mass of truck (m): 4
Truck
Measure & Record
Measure & Record
0.38-m
0.40-m
0.03-m
Truck
Truck + 0.060-Kg
Truck + 0.120-Kg
Truck + 0.180-Kg
5. Repeat varying the mass placed in the truck.
6. Calculate the average time, velocity, potential and kinetic energy. Formulas are provided.
7. Does the change in mass affect time and energy?
8. Explain why potential energy and kinetic energy are not the same.
Position from Start:
-m
Height (h): Measured
Gravity (g): 9.8 m/sec2
Force on truck (f): Measured
Mass of truck (m): Variable Timed Distance (d):
-m
Block Height
Time Trials
Experiment
Mass of
Truck
(Kg)
Height of
Truck (h)
(meters)
Trial
1
(sec.)
Trial
2
(sec.)
Trial
3
(sec.)
Speed
Average
Time
(seconds)
V=d/t
(m / sec)
-m
Energy
Potential
P.E.= mgh
(joules)
Kinetic
K.E.= ½
mv2
(joules)
1
2
3
4
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HOW IS THE KINETIC ENERGY OF A BODY AFFECTED
BY ITS MASS AND VELOCITY?
IDEA:
A body may have energy by virtue of its motion.
This type of energy is called kinetic energy. Kinetic
energy is directly proportional to both mass and speed.
PROCESS SKILLS:
Observing
Inferring
LEVEL: TEACHER
DURATION:. 30-40 min.
STUDENT BACKGROUND:
Students should be familiar with the metric system and know that energy is the
ability to do work.
ADVANCE PREPARATION:
The juice boxes (or milk canons) need to be partially filled with sand and adjusted
to be of equal mass. The amount of sand depends on the size of the boxes and the
masses of the cars used, as well as the surface on which they will be used.
Standard juice boxes filled about half way work well with metal "Hot Wheels"
cars on a "Formica" table top. Test out the amount of sand for the conditions
present
MANAGEMENT TIPS:
The boxes should be taped closed and students should be reminded not to open
them to avoid spilling sand around the room.
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
2. It moved (work done on it). The energy of motion of the car (kinetic
energy).
3. Yes. The faster the car is pushed, the more work it can do on the box.
4. The more speed an object has the more kinetic energy it has.
7. Yes. The box hit by the more massive car moves the most (has the most
work done on it).
8. The more mass an object has the more kinetic energy it has.
It should be emphasized that kinetic energy is directly proportional to both
mass and speed. In the upper grades the definition of K.E. = 1/2mv 2 can be
discussed, emphasizing that the speed is in the equation twice, (1/2mv2) and
therefore has an even greater effect on the kinetic energy than mass. The results of
this lab should be related to real cars, perhaps discussing how speed and mass
affect the amount of energy dissipated in an accident, or how they relate to fuel
economy.
Present activities or demonstrations of kinetic energy in everyday life such as
ones dealing with wind energy or water power. Look for examples of these in
your area such as windmills, sailboats, waterwheels, etc.
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WORKSHOP LEADERS' PLANNING GUIDE
CONSERVATION OF ENERGY
Previously it was demonstrated that energy may be transformed. This subtopic illustrates the concept of conservation of
energy. Conservation of energy means the total amount of energy before a transformation is equal to the total amount of
energy after a transformation. Because we live in a world of friction, energy often transforms to heat which can be hard to
measure accurately. This makes it very difficult to quantitatively prove that the amount of energy after a transformation is
indeed the same.
Although the conservation of energy is difficult to quantitatively prove. Idea A illustrates this concept in a qualitative way.
Idea B addresses why we are running out of energy even though it is conserved. Idea C deals with the special situation in
which energy can be converted into matter. and matter into energy. The meaning of E=mc 2 is discussed, and the energy
released when hydrogen is convened to helium is calculated. This calculation is relatively complex and intended as
optional background.
The ideas presented in subtopics I, II, and III are prerequisites for this subtopic.
Naive Ideas:
1. Energy is truly lost in many energy transformations.
2. There is no relationship between matter and energy.
3. If energy is conserved, why are we running out of it?
A. WHEN ENERGY IS CONVERTED FROM ONE FORM TO ANOTHER. THE TOTAL AMOUNT OF
ENERGY REMAINS THE SAME.
1. Activity: Energy Transformations and the Pendulum.
This activity uses a simple pendulum to illustrate conservation of energy.
2. Demonstration/Discussion: Stop and Go Balls. Coupled pendulums arc
used to demonstrate energy conservation.
3. Activity: Energy Transformations and the Hand Generator This activity uses a hand electric
generator (Genecon) to illustrate conservation of energy.
4. Discussion: What is Energy? Richard Feynman's essay on energy is used to
stimulate discussion.
B. EVEN THROUGH THE TOTAL AMOUNT OF ENERGY IN THE UNIVERSE IS CONSTANT IT IS NOT
ALWAYS IN A USEFUL FORM,
1. Activity: U the amount of energy in the universe is conserved, why must we conserve it?
This activity uses batteries and light bulbs to address the naive idea. "11 energy is conserved why are we running out
of it?"
C. IN SPECIAL SITUATIONS. LIKE NUCLEAR ENERGY, ENERGY CAN BE CONVERTED TO MATTER
AND MATTER INTO ENERGY.
1. Discussion - Focus on Physics: E = mc2
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IS ENERGY CONSERVED WHEN CONVERTED TO WORK?
Section 1: Is Energy Conserved When Force is Changed?
t
Finish – 2
Start
- t1
1. Set-up the equipment as indicated. Pease notice that this is the
same set-up used previously which investigated whether energy
Variables
Truck
depended on force. In this experiment we want to determine
Force
to
Move
Block
(f):
Measure
& Record
how much work can be done with the available energy we
Mass
of
truck
(m):
Measure
&
Record
measured. If you do not maintain the exactly the same set-up
Distance
Barrier
Moved
Measure
&
Record
previously, you will not be able to compare the energy and
(d):
work data.
Position from Start:
0.38-m
2. Hook the Newton scale on the barrier of wood and pull the
Independent
Variable
barrier as smoothly as possible along the surface where the
Block Height: 1
0.03-m
speed of the truck was measured. You should obtain constant
Block
Height:
2
0.06-m
reading of the Newton force, which you should record.
Block Height: 3
0.09-m
3. Place the wooden block at the beginning of the timed distance
labeled “Start t1”. Release the truck and measure the distance the truck pushes the wooden barrier. Repeat this
procedure for three trials.
4. Repeat changing the height of the support block. (This will affect the force of gravity acting on the truck.)
5. Copy your kinetic energy obtained previously and record it in your data chart. Review your data collected concerning
force and observe how force relates to the height.
6. Calculate the work done on the wooden barrier. Work = force x distance. Use the force needed to move the wooden
block and the distance the wooden block moved due to the application of the trucks kinetic energy.
7. Does the change in height (force) on the truck affect work done on the wooden barrier? _______________________
Note: the change in force on the truck was measured previously. The movement of the wooden barrier
indicated the amount of work. To answer the questions compare these two measurements.
8. Compare the work done by moving the wooden barrier to the amount of kinetic energy the truck had.
8.
Was energy conserved? Explain.
Position from Start:
Force to move block (f): Measured
Experiment
Block
Height
(m)
Force on
Truck
(Newton)
-m
Block Height: Given
Gravity (g): 9.8 m/sec2
Mass of truck (m):
-Kg
Distance (d) Block moves: Measured - chart
Force to
Distance Block Moves
Kinetic
Move
Work
Energy
Trial
Trial
Trial
Average W = f x d Calculated in
Wood
1
2
3
Barrier
(joules)
B-1
(meters)
(meters)
(meters)
(meters)
(Newton)
(joules)
1
2
3
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Section 2: Is Energy Conserved When Mass is Changed?
1. Set-up the equipment as indicated. Please notice that
this is the same set-up used which investigated
whether energy depended on mass.
In this
experiment we want to determine how much work
can be done with the available energy we measured
previously. If you do not maintain exactly the same
set-up previously used, you will not be able to
compare the energy and work data.
2. Measure the force needed to drag the wooden
barrier using the Newton scale.
Variables
Force to Move Block (f):
Distance Barrier Moved (d):
Position from Start:
Block Height:
Independent Variable
Mass of truck (m): 1
Mass of truck (m): 2
Mass of truck (m): 3
Small Truck
Measure & Record
Measure & Record
0.38-m
0.03-m
Truck
Truck + 0.060-Kg
Truck + 0.120-Kg
3. Measure the force of the truck using the Newton
scale. When measuring the force exerted by the
truck, hook the Newton scale on the truck and hold the body of the scale in your hand parallel to the ramp so the
weight of the scale does not pull on the truck.
4. Place the wooden barrier at the starting position (T1).
5. Release the truck and measure the distance the truck pushes the wooden barrier.
6. Repeat, varying the mass placed in the truck. This should affect the force of gravity acting on the truck. Measure
these forces using a Newton scale.
7. Calculate the work done moving the wooden barrier. Work = force x distance.
8. Does the change in mass of the truck affect work done moving the wooden barrier? __________________________
Note: The change in force was investigated previously. Work was measured by the movement of the wooden barrier.
To answer the above question compare these two measurements.
9.
Compare the work done on the wooden barrier to the initial kinetic energy of the truck.
10. Compare the work done on the wooden barrier to the potential energy of the truck as calculated.
Position from Start:
Force to move block (f): Measured
Experimen
t
Mass
(Kg)
-m
Block Height:
Mass of truck (m): Variable
Force to
Move
Wood
Barrier
(Newton)
-m
Gravity (g): 9.8 m/sec2
Distance (d) Block moves: Measured-chart
Distance Block Moves
Trial
1
(meters)
Trial
2
(meters)
Trial
3
(meters)
Average
Work
W=fxd
(meters)
(joules)
Kinetic
Energy
Calculated in
B-2
(joules)
1
2
3
4
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ENERGY TRANSFORMATIONS AND THE PENDULUM
Materials: string (see diagram to estimate length),
small weight (approx 1 N) pencil, metric
ruler
1.
Tie one end of a piece of string to the end of a
pencil. Have one member of the group hold the
pencil firmly on the edge of a desk with the string
hanging over the side. Tie the weight to the other
end so that it hangs just above the floor. Trim the
excess string. You have just made a pendulum.
It will be useful to help your understanding
of energy conservation.
2.
Tie a piece of string between the legs of the table as shown, positioning it about half way up from the floor. This string
will serve as a reference when you are observing the motion of the pendulum. (If you use small student desks, the same
thing can be accomplished by placing the pendulum on one desk, and tying the horizontal string to two other desks
which are positioned on each side of the pendulum.
3.
Pull the weight back to the height of the string. What kind of energy does the weight have at this point?
4.
Release the pendulum (don't push it!) and observe its motion for one complete swing (across and back). Where was it
traveling the fastest?
5.
What kind (or kinds) of energy did it have at this point?
6.
What kind (or kinds) of energy did it have halfway between the high point and the low point of its swing?
7.
What kind (or kinds) of energy did it have when it was at the opposite end of the swing from where it was released?
8.
Summarize you answers to questions 3-7 by describing the energy transformations that occur as a pendulum swings
from one side m the other and back.
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9.
Pull the weight back to the height of the stung and again release the pendulum, observing its motion for one
complete swing (across and back). Does it return to the same height as it started? Explain why or why not.
10. Pull the weight back to the height of the string and again release the pendulum, this time letting it make 5 complete
swings. On the last swing, did it return to the height from which you first released it? Explain why or why not using
energy.
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ENERGY TRANSFORMATIONS AND THE PENDULUM
IDEA:
When energy is converted from one form to
another, the total amount of energy remains
the same.
PROCESS SKILLS:
Observing
Inferring
LEVEL: TEACHER
DURATION: 30 min.
STUDENT BACKGROUND:
Students should be familiar with the concepts presented in the other sections of this
book.
ADVANCE PREPARATION:
MANAGEMENT TIPS:
Cut the string to the lengths required for the desks in the room you are using.
Almost any small object that has a weight of about 1 Newton (approx. 1/4 lb.) can be
used for the pendulum weight. Lighter objects can also be used. They are however
more affected by friction (mechanical energy losses due to conversion to heat
energy). Be sure that students don't give the pendulum a push as they release it
RESPONSES TO
SOME QUESTIONS:
3. Gravitational potential energy.
4. At the bottom, or low point of the swing.
5. Kinetic energy.
6. Gravitational potential energy and kinetic energy.
7. Gravitational potential energy.
8. Work is done to pick the weight up to the height of the string, and this gives the
weight gravitational potential energy. As the weight falls, its gravitational
potential energy decreases and its kinetic energy increases. At the bottom its
kinetic energy is at a maximum and its gravitational potential energy is zero.
On the way up the other side, the process is reversed -- kinetic energy
decreases and gravitational potential energy increases.
9. Yes (or fairly close). The total amount of energy is constant or conserved.
10. No. As the weight moves through the air. friction with the air and with the
string causes some of the mechanical to be converted to heat energy.
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
If no energy was converted to heat energy, the total mechanical energy
(potential + kinetic) at any point in the system would be constant As the pendulum
makes its first swing, very little energy is converted to heat energy and the weight
returns to Dearly the same height. As it continues to swing, the small amount of
mechanical energy lost to heat energy with each swing begins to add up, as shown by
the weight not returning to the original height. It is important to note that the energy
convened to heat energy is not destroyed or truly "lost" It merely leaves the
pendulum system and goes off into the air of the room and from there is spread out
around the universe. The energy leaves the pendulum, but it is not destroyed. Energy
is conserved!
POSSIBLE EXTENSIONS:
1. A playground swing could also be used to-illustrate the transfer of potential
energy to kinetic energy to potential energy.
2. A dramatic extension of this activity is to construct a heavy pendulum which is
supported by a strong pivot point on the ceiling, such as by tying it to an "I"
beam. The pendulum is adjusted so that when the weight is pulled back it comes
in contact with a person's nose when he or she is standing with their head against
a wall. When it is released (not pushed!) it will travel across the room and return
to a point close to the person's nose but not touching it Obviously, caution must
be exercised to insure that the rope used is strong and well-attached to the
weight and a strong support. It should be attached in a manner that prevents
slipping.
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STOP AND GO BALLS
(Demonstration/Discussion)
Tie about 50-75 cm of swings between two supports (the backs of two chairs work fine). Suspend two tennis balls from
the string using pieces of swing about 40 cm long. They should be about 20 cm apart (see diagram below).
Start one of the balls swinging. Now that the other ball begins to respond to this motion, and as its amplitude of swing
starts to increase, the ball that was initially moving starts to lose some of its energy. This continues until the ball that was
originally at rest is swinging with full amplitude, and the other ball comes to a complete stop. The cycle continues with
the balls transferring energy from one to the other.
The energy is transferred by the process of resonance, but it is not necessary to get into a discussion of the method at this
time. What should be pointed out is that energy is conserved. As one ball gives up its energy, it is gained by the other. Have
the participants reason out why the swings gradually diminish (heat losses due to friction at the knots, air resistance).
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COAT HANGER CANNON
EQUIPMENT: Coat Hanger Cannon: take a coat hanger and unbend it. The hanger end should be bent into a loop that can fit
over a support rod. Place a sharp bend, approximately. 2 cm. at the other end to hold the projectile.
Projectile: small piece of wood - approximately 2 cm. cube with a hole drilled in it, Metric ruler, Stop watch
Wire Hanger
height
Coat hanger Cannon Front View
Tabl
Table
range, time
floor
Coat hanger Cannon Side View
height
h
Trials
meter
mass
m
kg
acceleration
a
9.8 m / s
2
PE
mxa
Fxh
d
t
d/t
1/2 m x v2
newton
joule
meter
second
m/s
joule
range
time
velocity
KE
force
1
2
3
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ENERGY TRANSFORMATIONS AND THE HAND GENERATOR
Materials: 2 hand powered generators (Genecons), sets of clip leads for the generators, 1 miniature light bulb (7.5 volt) bulb
holder, 2 "D" cell batteries, masking tape
1.
Place the bulb in the bulb holder. Plug a set of clip leads into the generator and connect one of the clip leads to each
terminal on the bulb holder. Crank the handle of the generator and observe. Describe what happens in terms of energy
transformations.
2.
Tape the two batteries together in series (the positive terminal of one to the negative of the other). Hold one of the clip
leads from the generator to each of the remaining terminals. Describe what happens in terms of energy transformations.
3.
Connect the two generators to each other as shown. Using what you observed in the previous two steps, predict what will
happen when you turn the crank of one of the generators.
4.
Turn the crank of one of the generators. Describe what happens in terms of energy transformations.
5.
Turn the crank of the first generator ten revolutions while your partner counts how many revolutions the crank of the
second generator makes. Record the results.
Number of revolutions of the first generator
10
.
Number of revolutions of the second generator______________
6.
Did the two generators make exactly the same number of revolutions? Discuss why or why not in terms of energy
transformations.
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ENERGY TRANSFORMATIONS AND THE HAND GENERATOR
IDEA:
When energy is convened from one form to
another, the total amount of energy remains
the same.
PROCESS SKILLS:
Inferring
Observing
LEVEL: TEACHER
DURATION: 30 min.
STUDENT BACKGROUND:
Students should be familiar with the concepts presented in this book.
ADVANCE PREPARATION:
Gather the materials. Students need to be in groups of at least two.
MANAGEMENT TIPS:
A bulb with a voltage lower than 73 volts can be used in #1; however, if the
generator is cranked too rapidly, the bulb will blow out If battery holders are
available, then the taping together of batteries in #2 can be omitted. If tape is used,
the batteries have to be taped tightly to insure good contact. Pushing them together
when putting on clip-leads will also help to insure good contact. In #3 the polarity of
the connections does not make a difference. Let the students try it both ways. (The
direction in which the second generator turns will be reversed.)
RESPONSES TO
SOME QUESTIONS:
1.
2.
3.
4.
5.
6.
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
Mechanical energy is converted to electrical energy which is convened to light
and heat by the bulb. Heat energy and sound are also created by the friction in
the gears of the generator.
Chemical energy in the battery converts to electrical energy. When electrical
energy is put into a generator it becomes an electric motor and converts the
electrical energy into mechanical energy. As the generator turns, heat energy and
sound are also created by the friction in the gears.
When the first generator is cranked, the second one will turn.
When the first generator is turned, mechanical energy is convened to electrical
energy. This electrical energy goes into the second generator which converts it
back to mechanical energy. In the process, heat energy and sound are also created
by the friction in the gears of both of the generators.
Less than 10.
No. As the energy is convened from mechanical energy to electrical energy and
back to mechanical energy, some of it was converted to heat energy and sound
energy. This energy left the system and was not convened back to mechanical
energy.
When energy is convened from one form to another, the total amount of energy
remains the same. If during the conversion some of the energy is converted to a form
that leaves the system, the total amount remaining in the system will be reduced. For
example, in the third pan of the activity the heat energy and sound energy that were
created by the friction of the gears left the system and were not available to be
convened back to mechanical energy. It is important to emphasize that this energy is
not destroyed or truly "lost." It merely leaves the system and goes off into the air of
the room and from there is spread out around the universe. The energy leaves the
system, but it is not destroyed. Energy is conserved!
1. This activity can be easily related to activity “Energy Transformations and the
Pendulum”.
2. Ask students to write about the availability or "usefulness" of the heat energy
that was scattered about the universe in this activity. This should open the
door to an interesting discussion about why we are running out of energy if
the total amount of energy in the universe is conserved.
Energy ©2004 ScienceScene
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DETERMINING YOUR HORSEPOWER?
1. Determine your horsepower by timing yourself walking up a flight
of stairs.
power(watts)
horsepower
=
746 watts
power (watts)
=
work (joules) / time (seconds)
work (joules)
=
f (Newtons) x d (meters)
2. Distance is determined by measuring the height of one stair (in
meters) as shown in the illustration and counting the number of
stairs, you climbed, then multiply the height of one stair by the number of stairs.
distance = stair height x number of stairs
3. To determine the force that moved up the stairs take your weight, in pounds, which reflects the pull of gravity. Convert
this pull (force) to Newtons. Since one pound is approximately 4.5 Newtons, multiply your weight by 4.5
Newtons/pound to calculate the force in Newtons.
force = your weight x 4.5 Newtons/pound
5. The energy used in climbing the stairs can be determined by measuring the amount of work done. (Work = Force X
Distance). Note: the force is in Newtons and the distance in meters producing an answer with a label of Newtonmeters. Another name for a Newton-meter is called a joule. Express your work done in joules.
Work = Force x Distance
6. Determine the power that was exerted as you walked up the flight of stairs.
Power = work / time
Note: the answer will have a label of joules / second. This is the definition of a unit of power called the watt. Express
your power in watts.
7. Finally, let's see how we compare to our friend the horse by determining our horsepower.
Horsepower = power ( watts )
Force
Trial
F
(Newton)
Work
W=fxd
d
(meters)
w
(joules)
x
1 Hp
746 watts
Power
Power = work / time
t
(seconds)
p
(watts)
Horsepower
Hp = watts / 746
Hp
1
2
3
Average
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DETERMINING YOUR HORSEPOWER?
IDEA:
Energy is the ability to do work.
PROCESS SKILLS:
Measuring
LEVEL: TEACHER
DURATION: 20-30 min.
STUDENT BACKGROUND:
ADVANCE PREPARATION:
Familiarity with the metric system.
MANAGEMENT TIPS:
Participants should know their weight in pounds prior to this activity. Be sure
there is no horse play on the stairs which might result in injury.
RESPONSES TO
SOME QUESTIONS:
POINTS TO EMPHASIZE IN
THE SUMMARY DISCUSSION:
POSSIBLE EXTENSIONS:
Answers to questions vary.
1. When you are measuring work done against gravitational forces, only the
vertical distance between the two levels is needed. (This topic is covered in
detail in "SIMPLE MACHINES".) The work calculated in this lab is only the
work to move your body as a whole. Energy is also required for all the
internal processes (circulation, respiration, etc.) that keep you alive and and
for you m pick your legs up and down in the act of walking. The next activity
(IB4) is an excellent follow-up to this activity.
2. How does the amount of work done against gravity when someone walks up
the stairs compare to the work done against gravity when someone runs up
the stairs? (The sane).
1. Although the concept of power is covered in the workshop "SIMPLE
MACHINES" the students in the upper grades might be interested in
calculating the rate at which their legs can do work (or expend energy). This
rate is called power to do this, time the students as they run up the stairs..
Power = Work = Newton-Meters = Joules = Watts
Time
Sec.
Sec.
The unit of power is the watt. (Note: every 746 watts = 1 horsepower) Student
power values often come out high because they usually only run up one flight of
stairs. The values would lower drastically if they had to run up stairs for a whole
day!
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HOT ROD POWER
Determining the horsepower needed to lift an object
1. Determine the horsepower of a small battery powered car as it lifts a load (force) through a timed distance. Set-up the
equipment on the table top as indicated in the above figure. If the wheels spin you will need to wash them with soapy
water and possibly even the tabletop to get the best traction. To calculate Horsepower you will need to determine
force, work, and power.
Horsepower
=
power (watts)
work (joules)
=
=
power(watts)
746 watts
work (joules) / time (seconds)
f (newtons) x d (meters)
2. To determine force, obtain the mass (in Kilograms) of the object to be lifted by the battery powered car. Convert the
mass to Newtons by multiplying by 9.8 m/sec2. (You may wish to try other masses, but you will need a mass that the
car can pull.)
Force (Newtons) = mass in Kg x 9.8 m/sec2
3. To determine work identify and measure, on the track, the distance, in meters (approximately 0.50-m), that your car
pulls the load and multiply it times the force of the load being lifted.
work (in joules)
w= f x d
4. To determine power obtain the work and then divide it by the average time needed to lift the load.
power (watts)
p= w/t
5. To determine the horsepower divide the power, in watts, by the number of watts in a horsepower (746).
Horsepower
Force
F=mxg
Trial
m.
(Kg.)
g
(m/s2)
1
9.8
2
9.8
3
9.8
Average
9.8
power( watts) x
Work
W=fxd
F
(Newton)
d
(meters)
W
(joules)
Energy ©2004 ScienceScene
1 Hp
746 watts
=
Power
Power - work / time
t
(seconds)
P
(watts)
Horsepower
Hp= watts/746
Hp
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68
Relationship Between
Work, Kinetic and Potential Energy
(Let's look at the Units)
Work
= ∆ Kinetic Energy
f x d
= ∆ 1/2 M x v2
N x d
=
Kg x (m/s)2
m2
s2
Kg x m
x m
s2
=
Kg x
Kg x m2
s2
=
Kg x m2
s2
Joules
Joules
= ∆ Potential Energy
=∆f x d
=
N x d
= Kg x m x m
2
s
=
Kg x m2
s2
Joules
Units are really road signs which tell us where we are!!
Energy ©2004 ScienceScene
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ENERGY CONVERSION GAME
Produced by the Research Foundation of the State University of New York
with funding from the New York State Energy Research and Development Authority
One of the things that makes energy an important quantity in our lives is the many forms it can take. It can exist in
the form of motion. This is known as kinetic energy. The motion can be of different things. If the motion is of a
large object, the kinetic energy is said to be mechanical. If the moving objects are electrically charged, they are said
to form an electric current. If the moving objects are individual molecules, there are two possibilities. If their motion
is organized into waves, their kinetic energy is associated with sound. If their motion is completely disorganized,
their kinetic energy is associated with what we call heat (physicists call it “thermal energy”). Another form of
kinetic energy is light (and other forms of electromagnetic radiation, like radio waves and microwaves).
Other forms of energy do not have the form of motion, but they can cause an increase in motion at a later time.
Water at the top of a dam can spill over the dam. A battery can produce an electric current when it is connected into
a circuit. Fuels can be burned to produce heat. All of these are examples of potential energy.
Energy in one form, kinetic or potential, can be converted into any other form. The purpose of this activity is to give
you experience in identifying energy conversions in your life and the devices that bring about these conversions.
One way to see how many of these devices you can name is to fill in the energy conversion chart below. You will
learn more about energy conversion devices by playing the game “energy conversion dominoes,” described below.
Energy Conversion Chart: Energy exists in many forms in our everyday lives; among these forms are mechanical
(energy of motion of large objects), electrical, chemical, thermal, sound, and light. Energy in any of these forms can
be converted to energy in any other form. In the chart below, write the NAME OF A DEVICE that converts energy
from each form to another. Do this for as many cases as you can.
TO/FROM
Mechanical
Mechanical
Electrical
Chemical
Thermal
Sound
Light
Electrical
Chemical
Thermal
Sound
Light
Energy Conversion Dominoes: Cut out the 24 energy conversion dominoes on the handout. (For extra durability
they can be mounted on card stock beforehand.) Place them face down on a table. Distribute 12 of the dominoes
equally among the players. That is, two players will each draw six dominoes, three players will each draw four, four
players will each draw three, and five or six players will each draw two. (The game is not suitable for a larger
number of players.)
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In “regular” dominoes, the highest “double” is played first. The energy conversion dominoes corresponding
to “doubles” are those that convert a form of energy to the same form—for example, the refinery (converting one
form of chemical fuel to another chemical fuel), the transformer (converting electric energy to another form of
electric energy), and the drive shaft (converting one form of motion to another form of motion). Whoever has the
double beginning with the earliest letter of the alphabet (in the order “chemical,” “electrical,” and “motion”) plays it
first, and play continues counterclockwise from that point. Succeeding players complete their turn as follows: if they
have a domino in their hand that can connect to exposed ends of dominoes on the board (e.g., the internal
combustion engine, which uses chemical fuel, connected to the chemical fuel output of the refinery), they may play
one domino from their hand per turn. If they cannot properly play a domino from their hand, they must draw from
the still overturned dominoes (historically called the “graveyard”) until they draw a domino that can be properly
played. The first player to play all of his/her dominoes wins.
Note that proper play of the energy conversion dominoes requires not only matching the same forms of
energy but matching them in the same direction. That is, the energy output from one domino must match the energy
input to the domino adjacent to it. (This is not a requirement of regular dominoes!) An actual device corresponding
to the sequences of dominoes, which is characterized by a sequence of energy conversions, is known as a “Rube
Goldberg” device. You may have seen devices like this on sale at gift shops, particularly at airports.
Energy ©2004 ScienceScene
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electricity
light
transformer
electricity
electricity
rubbing objects
motion
heat
electricity
sound
internal
combustion
engine
motor
chem fuel
motion
electricity
motion
waste heat
absorber
speaker
sound
waste heat
electricity
sound
light
nuclear reactor
photocell
light
electricity
nuclear fuel
steam
generator
plant
Energy ©2004 ScienceScene
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motion
electricity
light
chem fuel
thermocouple
toaster
heat
electricity
electricity
heat
motion
light
drive shaft
fire
motion
motion
chem fuel
heat
motion
sound
battery charger
tuning fork
motion
sound
electricity
chem fuel
light bulb
glowing object
electricity
light
heat
light
waste heat
Energy ©2004 ScienceScene
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ear drum
battery
sound
motion
chem fuel
electricity
steam turbine
boiler
steam
motion
chem fuel
steam
waste heat
chem fuel
microphone
sound
electricity
refinery
chem fuel
chem fuel
chem fuel
Energy ©2004 ScienceScene
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ENERGY CONVERSIONS - Completed
How can one form of energy be converted to another form of energy?
In the chart write the name of an device that converts the form of energy listed along the left of the chart to the form of energy
listed along the top of the chart. For example: the conversion of light energy to mechanical occurs using a device called the
Radiometer.
Light
Light
Mechanical
Heat
Sound
Electrical
Chemical
Radiometer
Mechanical
Heat
Sound
Movement heat
Electrical
Chemical
1. Describe all steps in an energy chain beginning with the sun and ending with a light bulb.
Energy ©2004 ScienceScene
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Physical Science Materials Vendor List
Operation Physics Supplier
Arbor Scientific
P.O. Box 2750
Ann Arbor, Michigan
48106-2750
1-800-367-6695
Astronomy
Learning Technologies, Inc.
Project STAR
59 Walden Street
Cambridge, MA 02140
1-800-537-8703
The best diffraction grating I've found
Chemistry
Flinn Scientific Inc.
P.O. Box 219
Batavia, IL 60510
1-708-879-6900
Electronic Kits
Chaney Electronics, Inc.
P.O. Box 4116
Scottsdale, AZ 85261
1-800-227-7312
Electronic Kits
Mouser Electronics
958 N. Main
Mansfield, TX 76063-487
1-800-346-6873
All Electronics Corp.
905 S. Vermont Av.
Los Angeles, CA 90006
1-800-826-5432
Radio Shack
See Local Stores
Discount Science Supply (Compass)
28475 Greenfield Road
Southfield, Michigan 48076
Phone: 1-800-938-4459
Fax: 1-888-258-0220
Lasers
Metrologic
Coles Road at Route 42
Blackwood, NJ 08012
1-609-228-6673
laser pointers
Educational Toys
Oriental Trading Company, Inc.
P.O. Box 3407
Omaha, NE 68103
1-800-228-2269
Laser glasses
Magnets
The Magnet Source, Inc.
607 South Gilbert
Castle Rock, CO. 80104
1-888-293-9190
Dowling Magnets
P.O. Box 1829/21600 Eighth Street
Sonoma CA 95476
1-800-624-6381
KIPP Brothers, Inc.
240-242 So. Meridian St.
P.O. Box 157
Indianapolis, Indiana 46206
1-800-832-5477
Science Stuff - General
Edmund Scientific
101 E. Gloucester Pike
Barrington, NJ 08007-1380
1-609-573-6270
Materials for making telescopes
Rainbow Symphony, Inc.
6860 Canby Ave. #120
Reseda, California 91335
1-818-708-8400
Holographic stuff
Rhode Island Novelty
19 Industrial Lane
Johnston, RI 02919
1-800-528-5599
Marlin P. Jones & Associates, Inc
P.O. Box 12685
Lake Park, Fl 33403-0685
1-800-652-6733
U.S. Toy Company, Inc.
1227 East 119th
Grandview, MO 64030
1-800-255-6124
Natural Wonders
Nature Store
Flea Markets
Garage Sales
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