Name ______Class______Date ______

INQUIRY FOCUS • Observe 25 minutes

How High Does a Ball Bounce?

Energy is the ability to do work or cause change. The kinetic energy of a falling object increases as it falls because its speed increases.

Procedure

1. Hold a meter stick vertically with the zero-end on the floor. Line the bottom of the tennis ball up with the drop height mark.

2. As you drop the tennis ball from the 50-cm mark, your partner will observe the highest point to which the ball bounces. Your partner should sit in front of the meter stick in order to determine more easily the bounce height.

3. Repeat the trial three times at 50 cm. Create a data table and record the height of each bounce. Next, calculate and record the average height of the bounces at the 50-cm height.

Trial / Drop Height / Bounce Height
Trial 1 / 50 cm
50 cm
50 cm
50 cm average
Trial 2 / 100 cm
100 cm
100 cm
100 cm average
Trial 3 / 75 cm

4. Now drop the tennis ball from the 100-cm mark, as your partner observes the height to which the ball bounces.

5. Repeat the trial three times at 100-cm. Record the height of each bounce on the data table. Then calculate and record the average height of the bounces at the 100-cm height.

5. Using the data you have collected, predict how high the tennis ball will bounce if dropped from the 75-cm mark. Test your prediction. Record the height of the bounce on the data table.


Think It Over

1. How do potential and kinetic energy affect the height to which a dropped ball will bounce?

2. Does the height from which you drop a ball relate to the height to which the ball bounces? Use your data table to explain your answer.

3. How does the data collected by your group compare with the data collected by other groups?

4. What variables do you think might affect the height to which a dropped ball will bounce?

How High Does a Ball Bounce?:
Teacher Notes

Inquiry Focus

Observe—using senses to gather information about the energy of a falling ball and how some of that energy is reclaimed when the ball bounces back

Group Size Pairs or groups

Class Time 25 minutes

Safety

1. Students should wear safety goggles throughout the activity.

2. Instruct students not to throw the balls at anyone or anything.

Alternative Materials

Tennis balls work well, but any balls that bounce well will also work.

Procedure Tips

1. Encourage students to control the variables by using the same methods in each trial and by dropping the same ball onto the same surface.

2. Drop the balls onto a surface that is not carpeted for better bouncing results.

3. For dramatic comparison, have students test a “super ball” along with the tennis ball. A ball that doesn’t bounce at all could also be tested.

Answers

1. When the ball is dropped and pulled to the floor by gravity, potential energy is transformed to kinetic energy, which is greatest as the ball contacts the floor.

2. The ball bounces the highest when it is dropped from the greatest height. When the ball is held prior to the drop, it has stored, or gravitational potential energy. The higher the ball is held prior to the drop, the greater the amount of potential energy and the higher the bounce – but only up to a certain point because other variables have an effect.

3. Answers will vary but results should be similar if the methods and materials were the same.

4. Possible answers may include: the type of ball, drag, the surface onto which the ball is dropped, the height from which the ball is dropped, or the amount of pressure a ball has inside it.

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