Bouncing Ball Lab Name_________________________ Per___Date ____________________ Problem: How does energy change form in two different kinds of bouncing balls? Objective: You will determine the energy transformations in two different kinds of bouncing balls by collecting and analyzing drop height and bounce height data. Predictions: How do you think bounce height will depend on drop height for each kind of ball? Discuss both similarities and differences you expect to see. Materials: two different types of balls, meter stick Procedure: Drop each ball from heights of 40, 80, and 120 cm. Record your bounce height data for each ball in the data tables below. Data Tables: Experiment 1 – Type of Ball ________________________ Bounce Height (cm) Drop Height (cm) Trial 1 Trial 2 Trial 3 Average Experiment 2 – Type of Ball ________________________ Bounce Height (cm) Drop Height (cm) Trial 1 Trial 2 Trial 3 Average 1. Which is the manipulated variable in each experiment? Experiment 1: ________________________ Experiment 2: _____________________________ 2. Which is the responding variable in each experiment? Experiment 1: ________________________ Experiment 2: _____________________________ 3. What variables should be held fixed during each experiment? Experiment 1: ________________________ Experiment 2: _____________________________ ____________________________________ ________________________________________ 4. What variable changes from Experiment 1 to Experiment 2? 5. Why is it a good idea to carry out three trials for each drop height? Graph: Plot the data from both experiments on one sheet of graph paper. Remember to put your manipulated variable on the x-axis. Choose your scale carefully. Be sure to leave enough room for values larger than the ones you tested. Fit a “curve” to each set of the data points. Label each curve. 6. Describe your graphs. What patterns do you see? 7. Why do you think it’s a good idea to do two different experiments? Use your graph to answer questions 8-11. 8. a. The drop height of a tennis ball is 60 cm. Predict the bounce height. _________________ b. Check your prediction experimentally. What is the actual bounce height? ____________ 9. a. The tennis ball bounces to a height of 55 cm. Predict the drop height. ___________ b. Check your prediction experimentally. Was your bounce height close to 55 cm? ________ 10. a. The drop height of the racquetball is 1 meter. Predict the bounce height. _____________ b. Check your prediction experimentally. What is the actual bounce height? ____________ 11. a. The racquetball rebounds to a height of 75 cm. Predict the drop height. ____________ b. Check your prediction experimentally. Was your bounce height close to 75 cm? ________ 12. You find a strange ball on the playground. Because you have been investigating bouncing balls, you drop the ball from a height of 50 cm. It bounces back to a height of 18 cm. Is it more like the tennis ball or the racquetball? Why do you think so? 13. If you did your experiment with the tennis ball on a soft rug instead of on your classroom floor, would the curve you obtained be more like Curve X or Curve Y? Explain your choice. 14. Fill in this table for an experiment using a different rubber ball. Show any work you do. Drop Height Bounce Height 40 cm 30 cm 60 cm 100 cm Analysis and Conclusions: 15. What kind of energy does the ball have just before it is released? 16. What kind of energy does the ball have just before it strikes the floor? 17. What happens to the ball’s kinetic energy (KE) and potential energy (PE) as it falls? 18. What happens to the ball’s KE and PE as it bounces back upwards? 19. a. Which kind of ball loses more energy in each bounce? How can you tell? b. Where does the lost energy go? c. What is true about the total amount of energy, in all forms, in the system of the ball and its surroundings? 20. If 100% of the ball’s KE were converted back to PE, how high would it bounce? Critical Thinking and Applications: Imagine that you own a chain of toy stores. An inventor claims to have developed a new kind of ball, called Rocketball, that bounces better than anything already on the market. He wants you to buy Rocketballs and sell them in your stores. He sends you data which is summarized in this data table. Rocketball Bounce Heights, in Centimeters Average Height of Average Height of Average Height of Original Height Bounce 1 Bounce 2 Bounce 3 200 215 217 190 100 110 102 95 50 60 48 49 Analyze the inventor’s data. Write him a brief letter on the back of this sheet identifying at least three specific pieces of bounce height data that you know cannot be correct. Explain how you can tell the data are inaccurate based on the data you collected during this investigation and on the law of Conservation of Energy. .