1- Obtaining a Baseline
- How did the release height affect the rebound height?
(The greater the height of the drop, the greater the rebound
- Did you observe a difference in the ball's shape as it
struck the ground? If so, what happened?
(The shape deformed and temporarily stored the energy of
the collision. Instantly, it "popped back" into its spherical
shape, driving the ball's upward rebound.)
- Was the relationship between release height and rebound
height constant? In other words, did the ball bounce highest
when released from the highest point?
(No. At a medium drop height, the ball bounced back the
greatest percentage of its release height.)
- CRITICAL ANALYSIS: At a certain point, further increases
in height do not produce a higher rebound height. Explain.
(At a certain release height, the ball will undergo its
maximum disfiguration upon contact with the ground. Additional
increases in drop height will not increase the disfiguration.
Therefore, there is a limit to the amount of energy that
can be stored and the shape change produced by the impact.)
2- Cooling Off
- Did the rebound height change when the golf ball and
baseball were refrigerated?
(Yes. They did not bounce as high.)
- Which ball's rebound was affected most by the change in
(The golf ball.)
- How would you find the percentage of the bounce lost due
(Subtract the height of the "cooled" bounce from the
initial bounce height. Then, divide this difference by the
initial bounce height. Multiply by 100 to obtain a percentage.)
- What percentage of the bounce is lost when a baseball
- What percentage of the bounce is lost when a golf ball
- Why does the change in temperature affect the bounce?
(When cooled, the material doesn't disfigure as easily.
Since its shape "squishes" less, it stores less potential
energy. Since less energy is stored, the bounce is not as
Transfer of Energy
with the sun, identify all of the energy changes responsible
for a basketball's rebound. To simplify matters, assume that
the basketball is already manufactured.
(The sun's energy is absorbed by green plants. Green plants
are eaten by herbivores, and energy is transferred and stored
in the animals. Herbivores are eaten by humans, and energy
is transferred and stored in the body. Stored body energy
is changed into muscle movement. Movements increase the potential
energy in the lifted ball. The falling ball exhibits the change
of physical energy to kinetic energy. Upon striking the surface,
kinetic energy is changed into the physical energy of the
deformation. Physical energy is changed back to kinetic energy
with the rebound bounce.)