Bouncy Ball Lab: Conservation of Energy
Purpose: The purpose of this lab is to explore the energy losses during the repeated (mostly) elastic collisions between a
ball and the floor after being dropped from a certain height.
Materials: a ping pong ball, a golf ball, a tennis ball, a meter-stick, good eye-sight, sense of adventure
Procedure:
1.
Drop one of the balls from a height of 1 meter very close to a meter stick with “zero” being at the bottom. A 2 nd
person will eyeball the height of the first bounce and record it. Keep eyes level horizontally between the ball and the
meter-stick to avoid looking at an angle.
2.
Drop the same ball from one meter again and have the 2 nd person measure the height of the second bounce only.
3.
Drop the same ball continuously with your partner recording the height of each successive bounce. You should only
be measuring the height of a single bounce each trial run. Continue measuring the height of each bounce until the
height reaches less than 5 cm.
4.
Fill in the table recording PE, KE, Vf, and % energy lost for each bounce.
5.
Complete two more tables using the two other kinds of balls.
6.
Answer the questions in the Data Analysis and Error Analysis sections.
ball type: __________________________
ball type: ______________________________
ball type: __________________________
ball type: __________________________ (extra table)
Data Analysis:
1.
What is the average percent energy loss per bounce for each type of ball?
Tennis ball
Golf ball
Ping pong ball
Average % energy loss per
bounce (%/bounce)
2.
For each type of ball, determine the formula that will tell you the height h after n bounces when dropped from an initial height H. (hint: your formula
should be solved for h in terms of H, n, and a constant that is related to your energy retained per bounce)
3.
The height of the freshman hallway balcony is 5.245 meters. How many bounces before the bounce height is less than 0.50 meters high? Use your
equations from #2 to solve for n bounces for all three types of balls.
4.
Go to the freshman balcony and drop the tennis ball and golf ball to test your equations.
predicted tennis ball bounces to under 0.50 m:
actual tennis ball bounces:
predicted golf ball bounces to under 0.50 m:
actual golf ball bounces:
Error Analysis:
Why would dropping the ping pong ball from the freshman balcony to test your formula’s prediction be a waste of time?
Why did your results from #4 above differ from your predictions in #3?