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On the Ball
 
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PROCEDURE
Part 1- Obtaining a Baseline

QUESTIONS

  1. How did the release height affect the rebound height?
    (The greater the height of the drop, the greater the rebound height.)
  2. 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.)
  3. 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.)
  4. 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.)


Part 2- Cooling Off

QUESTIONS

  1. Did the rebound height change when the golf ball and baseball were refrigerated?
    (Yes. They did not bounce as high.)
  2. Which ball's rebound was affected most by the change in temperature?
    (The golf ball.)
  3. How would you find the percentage of the bounce lost due to refrigeration?
    (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.)
  4. What percentage of the bounce is lost when a baseball is refrigerated?
    (About 15-20%)
  5. What percentage of the bounce is lost when a golf ball is refrigerated?
    (20-30%)
  6. 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 great).

EXTENSIONS

Transfer of Energy
Beginning 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.)

 

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