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Bounce Lab Follow Up Notes
Background information: Energy causes things to happen. During the
day, the sun gives off light and heat energy. At night, street lamps convert electrical
energy to light energy. As a car drives by you, it converts chemical energy stored in the
gasoline into mechanical energy. Our bodies convert chemical energy in the food we
eat to kinetic energy we need to play or study.
Energy is defined as the ability to do work or cause the change in the speed,
direction, shape, or temperature of an object. Work is done when a force causes an
object to move in the direction of the force. There is a very close relationship between
work and energy. Both work and energy are measured in Joules. Energy has several
forms. Mechanical Energy is the total energy of motion and position of an object.
Both potential and kinetic energy are kinds of mechanical energy.
1) Potential Energy – energy that is stored (energy of position or height).
 If you stretch a rubber band, you will give it potential energy. As
the rubber band is released, potential energy is changed to motion
or kinetic energy.
 The chemical energy in a can of gasoline, the energy in a rubber
ball before it is dropped, and the energy in water behind a dam are
all examples of potential energy.
 Gravitational potential energy is the energy stored in an object as the result of
its height. The higher the object, the greater its potential energy.
 There is a relationship between the mass of an object and its gravitational
potential energy. The more massive an object is, the greater its potential energy.
2) Kinetic Energy – energy that is moving, (energy of motion).
 A rubber band flying through the air has kinetic energy, a bouncing ball has
kinetic energy, and you have kinetic as you are walking to class.
 Kinetic energy is related to both mass and speed. The greater the mass or speed
of an object, the greater the kinetic energy.
 Even when an object seems to be at rest, its atoms and molecules are in
constant motion and thus have kinetic energy. The average kinetic energy of the
atoms or molecules is measured by the temperature of the body.
Potential energy is converted into kinetic energy.
 For example – A waterfall has both potential and kinetic energy. The water at the
top of a waterfall has potential energy. When the water begins to fall, its potential
energy is changed into kinetic energy. This change in energy happens at Niagara
Falls where it is used to provide electricity from the transformation of mechanical
and electromagnetic energy to parts of the northeastern United States. It does
not take much effort to lift a ball off the ground. However, work is being done to
the ball as it is being lifted, giving it energy. When the ball is dropped, the ball
begins to move. The potential energy is converted into kinetic energy.
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Other Forms of Energy:
 Thermal Energy-all matter is made of particles (atoms and molecules) in
random motion. Because the particles are in motion, they have kinetic energy.
Thermal energy is all of the kinetic energy due to random motion of the particles
that make up an object.
 Chemical Energy-is the energy that is released when compounds are broken
apart. Chemical energy is released when our bodies digest food, when wood
burns, when a match is lit, or when we use batteries. It is stored energy so
therefore it is a form of potential energy.
 Electrical Energy-is the energy of moving electrons. Electrical energy is used
when you plug anything in to a socket.
 Sound Energy-is energy caused by vibration. When you stretch a guitar string,
the string stores potential energy. When the string is released the potential
energy is converted to kinetic energy, which makes the strings vibrate. The
vibrations move to the air around and the air transmits the vibrations to your ear.
 Light Energy-is produced by the vibration of electrically charged particles, but
light, unlike sound, can move through empty space.
 Nuclear Energy-energy that comes from the nucleus of an atom. Atoms store a
lot of potential energy. When nuclei join together, it creates a fusion reaction.
The sun and stars produce energy this way. When a nucleus is split apart, it
creates a fission reaction. Fission is used to generate power at nuclear power
plants.
Energy is conserved.
 When you drop a ball, the potential energy is changed into kinetic energy. When
the ball bounces to a lower and lower height, it is not losing energy. As the falling
ball rubs against the air, some of the kinetic energy is changed into heat. Some
energy changes into sound when the ball hits the floor. Because some energy
becomes unusable when it changes from one form to another, the ball will never
have enough energy to bounce back up to its starting height. In any conversion
of energy, some of the energy becomes unavailable for future use. The Law of
Conservation of Energy states, energy can be neither created nor
destroyed, but it can be converted from one form to another and it can be
transferred from one object to another. You can't ever get as much energy
out of a transformation as you put into it.
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Bounce!
Be very careful with the balls.
Do not throw them!
DROP the balls as instructed in the
procedure.
Problem: To observe the relationship between potential and kinetic energy.
Materials: Meter tape, Masking tape, Pen/Pencil, Tennis Ball, Whiffle Ball
Procedure:
1.
Starting at the floor, stretch a meter tape vertically against the wall making sure
that the 1.0 cm mark is on the bottom touching the floor.
2.
Hold the tennis ball at the 50cm meter mark and drop it. Observe carefully as
the ball bounces.
3.
Measure and record the bounce height of the tennis ball.
4.
Repeat steps 2 – 3 for a total of 3 trials.
5.
Hold the ball at the 75cm mark and repeat for 3 trials.
6.
Hold the ball at the 100cm mark and repeat for 3 trials.
7.
Repeat steps 2-6 for the whiffle ball.
8.
Find the mean bounce height for each drop height.
Data:
Starting Height
50 cm
75 cm
100 cm
Trial 1
Tennis Ball Bounce Height
Trial 2
Trial 3
Starting Height
50 cm
75 cm
100 cm
Trial 1
Whiffle Ball Bounce Height
Trial 2
Trial 3
Mean
Mean
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Data Analysis: Make a bar graph to compare the mean bounce height at different
starting heights. Remember to title and label your graph and remember to use
different colors.
Title: ______________________________________________________________
Questions:
1. Describe the similarities and differences that you saw between the 3 drop heights?
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2. Which height has more potential energy?
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3. Why doesn’t the ball bounce back up to the drop height? Where does the energy go?
Remember…energy cannot be created or destroyed!
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