1. Measure the height of the staircase you will be running up. We will call this Ah. If you use feet or inches you will need to convert the height to meters (1 ft = 12 in, 1 in = 0.0254 m). Measured height in m (Ab):2 2. Start from rest at the bottom of the staircase and run to the top, timing yourself as you go. Record the time to the nearest 0.1 seconds. Time 1: Time 2: Time 3: Time 4: Time 5: Average time 3 2.9 3.2 3.1 3_ in s (At):3 3. Measure your weight in pounds and then convert this to newtons (1 (b = 4.45 N). Measured weight Measured weight in los: 112_ in N:498.4 4. Find your mass in kg from your weight in newtons. Recall that (weight) = mg, where g = 9.8 m/s2. 1 Mass in kg (m):498.4/9.8=50.95. Calculate the change in gravitational energy you experience as you ascend the stairs: AB}; = mgAh. The unit of energy is the joule (J), where U = 1 N m = 1 kg mZ/sz. Change in m in J (gggzso.9*9.s*2= 997.6 6. Finally, power is the rate at which energy is converted from one form to another, or the work done per unit time. For this process, P = AEg /At. Calculate the average power output you had for your five trials. The unit for power is the watt (W), where 1 W = 1 Us. Power output in W (P):997.6/3=332.5 7. Suppose the power output you found in Question 6 is the same power you could produce on a stationary bike, and suppose we hooked up a mechanical generator to the bike, and we hooked up lightbulbs to the output of the generator. How many 60 W lightbulbs could you power (simultaneously) by riding the bike as hard as you can? Would you be able to keep them running for very long? Explain your reasoning. 8. In terms of energy, why is it important to start from rest at the bottom of the staircase, instead of giving yourself a running start? *9 Procedure for Part 2: Comparison of elasticity In this part you will measure the elasticity of balls. Elasticity measures how much energy is \"lost\" in a collision, meaning how much kinetic energy gets transformed into thermal energy and does not show up as kinetic energy after the collision. Specifically you will explore whether the elasticity is affected by the height of the drop as well as compare elasticity between two different types of balls. Choose two different types of ball and for each one, drop it from a known height and measure the height it rebounds to. Record the initial and final heights in the tables. Repeat this process for ten different heights over as wide a range as you can. Next analyze the data you collected by calculating the fraction of the initial gravitational energy that was retrieved when the ball reached its final height. Calculate the fraction of the initial gravitational energy that was lost to the thermal energy somewhere in the process. Record these both in the data tables as either decimals (such as 0.56) or percents (56%). Lastly, calculate the averages of the two fractions. Once you have completed the data tables, answer these two questions: 9. Consider both balls. Does the fraction of gravitational energy retrieved change systematically for different heights or is the variation just random? 10. How do the average fractions of energy retrieved/lost compare between the two balls you used? Discuss this in a few sentences. Type of ball basketball m=0.598 kg Trial Initial height Final height Fraction of Grave retrieved Fraction of GravE "lost" to after bounce thermal energy 1 1.04(m) 0.3 2 0.75 0.26 3 1.1 0.37 4 1.2 0.42 5 0.5 0.14 6 1.5 0.59 7 1.71 0.68 8 0.3 0.08 9 0.7 0.23 10 0.9 0.33 Average of 10 trials Type of ball cat ball m=0.073 kg Trial Initial height Final height Fraction of GravE retrieved Fraction of GravE "lost" to after bounce thermal energy 1 1.04(m) 0.46 2 1.1 0.42 3 1.2 0.51 4 0.75 0.3 5 0.5 0.15 6 1.5 0.57 7 1.71 0.6 8 0.3 0.11 9 0.7 0.28 10 0.9 0.35 Average of 10 trials