Rubber Band Lab Purpose: Determine the mechanical work needed to stretch a rubber band. Determine the elastic potential energy in the stretched rubber band. Determine the rubber band’s kinetic energy as it flies as a horizontal projectile. Determine the rubber band’s elasticity constant. Procedures: 1. Measure rubber band’s mass by using a triple beam balance. Record it in the Data Table. 2. Set up a rubber band launcher by placing the rubber band on the end of the ruler. 3. Measure the amount of force needed to stretch the rubber band 12 cm (0.12 m) beyond its normal length. Record it in the Data Table. 4. Position the rubber band ruler launcher at the edge of your stool. Measure the vertical height of the rubber band above the floor. Record it in the Data Table. 5. Pull the rubber band to its 0.12 m stretched length. Release it so that it flies through the room. Be sure to identify the exact landing position of the rubber band. Measure the rubber band’s range. Record it in the Data Table. 6. Repeat procedure 4 two more times and determine the rubber band’s average range. 7. Calculate the flight time of the rubber band by using horizontal launch projectile strategies. 8. Calculate the mechanical work for stretching the rubber band. 9. Determine the elastic potential energy stored in the rubber band when it is stretched. 9. Calculate the average horizontal velocity of the rubber band. (Be sure to use the average range and the calculated flight time data.) 10. Calculate the average kinetic energy of the rubber band as it flew through the air. 11. Calculate the rubber band’s elastic constant. 12. Complete the Conclusion Questions.

Data Table Rubber band mass = ___________kg

Applied Force for stretching the rubber band 0.12 m _________N

Rubber band height above the floor for horizontal projectile launch _____________m Rubber band range: Trial 1 _________m

Trial 2 _________m

Trial 3 _________m

Average _________m

Rubber band Flight time Calculation – This is a horizontal projectile launch event. (show formula, work, and round to the nearest ten thousandth after every math operation)

vi = _____m/s d height = __________m g = __________m/s2 Mechanical Work for rubber band stretch (show formula, work, & round to the nearest ten thousandth after every math operation) FA = ________N d stretch = __________m Determine the rubber band’s elastic potential energy stored in the rubber band when it is at its stretched length. (be sure to identify the energy relationship that allowed you to identify the elastic potential energy)

Horizontal velocity for rubber band (show formula, work, and round to the nearest ten thousandth after every math operation) t flight = ________s d range = __________m Kinetic Energy for flying rubber band (show formula, work, and round to the nearest ten thousandth after every math operation) m rubber band = ________kg v rubber band = __________m/s Elastic constant for rubber band (show formula, work, and round to the nearest ten thousandth after every math operation) PE rubber band = ________J d stretch = __________m

Conclusion Questions 1. Compare the mechanical work for stretching the rubber band 0.12 m to the average kinetic energy of the rubber band during its horizontal projectile flight. Be sure to explain why these indirect measurements are similar or different. Be sure to remember human error aspect of testing.

2. How would the mechanical work for stretching the rubber band compare to the elastic potential energy of the stretched rubber band . Be sure to explain why these indirect measurements are going to be similar or different.

3. How would the kinetic energy for the flying rubber band compare to the elastic potential energy of the stretched rubber band . Be sure to explain why these indirect measurements are going to be similar or different.

4. If you did repeated procedure for five hundred times, would the kinetic energy for the flying rubber band be the same as what was discovered in this lab investigation? Explain.

5. Repeatedly stretch a rubber band and then release it back to its normal length in a very rapid fashion for 45 seconds. Immediately after the 45 seconds of repeated stretching, place the rubber band next to your cheek. What do you observe about the rubber band? Explain the observation.