Download Elastic Potential Energy

Elastic Potential Energy
Rubber Band Experiment [picture]
A simple way to demonstrate elastic energy is to stretch a rubber band
and not let go, the stretch demonstrates potential energy. Let go of the
rubber aiming it toward a wall and it is converted to kinetic energy.
The rubber band can also illustrate energy conversion. Place the band
against your upper lip to measure its temperature. Stretch and release the
band repeatedly. Test the temperature again. It should feel warmer. Why does it feel
warmer and where do you think the heat energy came from?
Gravitational Potential Energy
Basketball Bounce
Materials: basketball, hard floor or pavement to bounce ball on
To demonstrate gravitational potential energy hold a basketball over your head and
release it on to the pavement. Gravity pulls the ball towards the Earth creating kinetic
energy as it drops until it hits the pavement converting it back to potential. This
conversion from potential to kinetic is repeated as the ball bounces up and down the
pavement.
When you drop the ball, note how high it bounces back. Why doesn't it bounce back to
the same height at which you let it go? If you let the ball keep bouncing, notice that with
it bounces back a little lower each time.
If the ball were to bounce back to the same height at which it was dropped, that would
mean all the gravitational energy was converted to kinetic energy. It isn't all movement,
though is it? Listen (that's a hint), what other forms of energy can you detect or identify?
Think back, too, to the rubber band experiment--can you think of another energy form?
Roll-back Toy [add picture of steps]
Materials:
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A small container that can be laid on its side and rolled and have a hole punched
in its top and bottom (such as a clear plastic soda bottle or coffee can)
Note: Using a clear soda bottle helps to demonstrate what
is happening inside.
One thick rubber band about 3-4 inches long (8-10 cm)
Two tooth picks or paper clips
Several washers tied together with a twist tie or another weighting device that will
fit through the opening of a soda bottle or the container being used.
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String
Hole punch tool or scissors
Procedure: Punch a hole through the lid and the bottom of the container. Take the lid off
the container. Thread a string through the bottom of the container and pull it through the
lidless top of the container (make sure there is still string hanging out the bottom end).
Tie the end of the string that you pulled through the top to one end of the rubber band
(you will use the string as a lead to help thread the rubber band through the container).
Tape the washers together and then connect them to the middle of one section of the
rubber band (do not tape the strands of the rubber band together).
Put the end of the rubber band (the end not connected to the string) through the container
lid. Use a toothpick to secure the band so that it does not slip inside the container (put the
toothpick through the end loop of the rubber band that remains outside the hole). Put the
lid on the container (making sure the string is still sticking out the other end).
Carefully pull on the thread until the rubber band comes through the hole. Secure the
band with the second tooth pick. Be sure to situate the weight so it is in the center of the
container and does not touch the sides. Your roll-back toy is ready to go!
Activity: Roll the toy and watch as the weight holds one strand of the rubber band
stationary while the free side twists around. The farther the toy is rolled the more
potential energy. Release and watch the toy roll back towards you demonstrating kinetic
energy. This would be a great activity to have races in the classroom to see who could
devise the roll-back toy with the greatest potential energy.
Potential and Kinetic Energy
Suggested Grades
4+
Objective
Students will observe and record the amount of work done by marbles rolling down a
plane and more fully understand the relationship between potential and kinetic energy.
Materials
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3 different sized marbles
a ramp
metre stick
milk carton.
Method
Can be performed as a(n) individual, group, or demonstration activity.
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Cut off the top part of a milk carton.
Set up the ramp with the cut milk carton at the bottom (the open end of the carton
should face the top of the ramp). Place a metre stick also at the bottom of the
ramp beside the milk carton.
Hold the medium sized marble at the top of the ramp. Ask students to predict how
far the marble will push the carton once it gets to the bottom of the ramp.
Let the marble go. Record the distance that the marble was able to push the
carton.
Hold the largest marblee at the top of the ramp. Ask students to predict whether
the marble will push the carton further or less further than the previous marble.
Let the marble go. Record the distance that the marble was able to push the
carton.
Repeat with the smallest marble.
Explain to students that the marble, when held at the top of the ramp, had
potential energy. The energy was waiting to be used. Once the marble was let go,
its energy changed into kinetic energy, moving energy. This kinetic energy was
then transferred to the milk carton which caused it to also move. Additionally the
heavier and larger the marble is, the more potential energy it would have, the
faster it would travel, and the further the milk carton would move.
Demonstrate the experiment again.
Extension: Try letting the marble go at different spots on the ramp. What
happens?
www.CanTeach.ca
What is energy?
Energy makes change; it does things for us. It moves cars along the road and boats over
the water. It bakes a cake in the oven and keeps ice frozen in the freezer. It plays our
favorite songs on the radio and lights our homes. Energy makes our bodies grow and
allows our minds to think. Scientists define energy as the ability to do work. People have
learned how to change energy from one form to another so that we can do work more
easily and live more comfortably.
Forms of Energy
Energy is found in different forms, such as light, heat, sound and motion. There are many
forms of energy, but they can all be put into two categories: kinetic and potential.
KINETIC ENERGY
POTENTIAL ENERGY
Kinetic energy is motion––of
Potential energy is stored energy
waves, electrons, atoms, molecules, and the energy of position––
substances, and objects.
gravitational energy. There are
several forms of potential energy.
Electrical Energy is the movement Chemical Energy is energy stored
of electrical charges. Everything is in the bonds of atoms and molecules.
made of tiny particles called atoms. It is the energy that holds these
Atoms are made of even smaller
particles together. Biomass,
particles called electrons, protons,
petroleum, natural gas, and propane
and neutrons. Applying a force can are examples of stored chemical
make some of the electrons move.
energy.
Electrical charges moving through a
wire is called electricity. Lightning is Stored Mechanical Energy is
another example of electrical energy. energy stored in objects by the
application of a force. Compressed
Radiant Energy is electromagnetic springs and stretched rubber bands
energy that travels in transverse
are examples of stored mechanical
waves. Radiant energy includes
energy.
visible light, x-rays, gamma rays and
radio waves. Light is one type of
Nuclear Energy is energy stored in
radiant energy. Solar energy is an
the nucleus of an atom––the energy
example of radiant energy.
that holds the nucleus together. The
energy can be released when the
Thermal Energy, or heat, is the
nuclei are combined or split apart.
internal energy in substances––the Nuclear power plants split the nuclei
vibration and movement of the atoms of uranium atoms in a process called
and molecules within substances.
fission. The sun combines the nuclei
Geothermal energy is an example of of hydrogen atoms in a process
thermal energy.
called fusion. Scientists are working
on creating fusion energy on earth,
Motion Energy is the movement of so that someday there might be
fusion power plants.
objects and substances from one
place to another. Objects and
substances move when a force is
Gravitational Energy is the energy
applied according to Newton’s Laws of position or place. A rock resting at
of Motion. Wind is an example of
the top of a hill contains gravitational
motion energy.
potential energy. Hydropower, such
as water in a reservoir behind a dam,
is an example of gravitational
Sound is the movement of energy
through substances in longitudinal potential energy.
(compression/rarefaction) waves.
Sound is produced when a force
causes an object or substance to
vibrate––the energy is transferred
through the substance in a wave.