Bouncing Balls (Energy Transfer)

Potential to Kinetic

1)Select three different balls.

2)Find each balls mass in kilograms.

3)Drop each ball 3 times, from 3 different heights. (A total of nine drops per ball)

4)Measure the height that each ball bounces.

5)Worksheet Changes!

  1. K.E. initial to P.E. initial
  2. K.E. final to P.E. final
  3. % K.E. Lost to % of Energy change

6)Key equations

  1. K.E. = (1/2) * m * v2
  2. P.E. = m * g * h
  3. Vf =  (2 * g * h)
  4. Work (Joule) = Force * distance

7)Fill in the data table using Excel…or you can complete it using your calculator.

Name______Date______Hour______

Bouncing Balls…

Goal:

To find the fraction (%) of Energy transferred in various balls after they’ve collided with the ground. Make sure to test each ball on the same surface (tile, rubber, carpet, etc)

Procedure:

You must select three different types of balls, in which you will bounce. Each ball will be dropped from a height of 1 meter (3 times), for a total of nine drops.

Ball #1 / Ball #2 / Ball #3
Ball Description
Ball Mass (kg)
Height Dropped - 1m / 1.
2.
3.
Height of 1stBounced (m) / 1.
2.
3.
P.E. Initial (Joules) / 1.
2.
3.
P.E. Final at top of 1stbounce (Joules) / 1.
2.
3.
% of PE lost / 1.
2.
3.

Questions:

  1. Which ball had the lowest amount of its Energy lost? Why do you think this ball had such an “efficient” collision with the floor? Which ball had the highest amount of its Energy lost? Why do you think it was so inefficient in its collision?
  1. Do you think that the type of flooring that you dropped your ball on had any effect on how it bounced? Describe what you think would happen if you dropped your ball on shag carpet vs. dropping it on smooth/hard concrete.
  1. Do you think the initial height that you dropped your balls from have any effect on the percentage of Energy lost? Why or why not...explain?
  1. Describe how the Kinetic Energy of a ball changes from the second it is released to the instant just before it hits the ground. What is happening to the balls Kinetic Energy as it falls through the air?
  1. If a 50-kg “perfect bouncing ball” (it will bounce back up to the height it was dropped) was dropped from a height of 10 meters, how much work (in joules) is done on the ball by gravity? How much Kinetic Energy (initial) does the ball have the instant before is hits the ground?
  1. What relationship do you see between “Work” and Kinetic Energy? What is our current definition of Kinetic Energy? Work?
  2. Eg (potential energy due to gravity) is the “stored” energy. The equation for potential energy is (Eg (joules) = mass * gravity * height) this is the same equation as work, (Work = Force * distance). Explain what happens to the PE of a ball the instant it is released until it hits the ground.
  1. Fill in the data table below for the highest ball that you dropped. It might be much faster to enter the data into a spreadsheet…like Excel!

Height = ______meters. Mass = ______kg.

Potential Energy / Kinetic Energy
Starting Height (h):_____
0.95 * h
0.90 * h
0.85 * h
0.80 * h
0.75 * h
0.70 * h
0.65 * h
0.60 * h
0.55 * h
0.50 * h
0.45 * h
0.40 * h
0.35 * h
0.30 * h
0.25 * h
0.20 * h
0.15 * h
0.10 * h
0.05 * h
  1. What relationship did you find between Potential Energy and Kinetic Energy as the ball is falling through the air (This is an important relationship…it proves one of our laws)?
  1. On Excel graph the relationship between PE and KE vs. height from the data on this table.