# Energy and Energy Transformations

(Due date: Saturday, 7/18, 11:59 pm)

Steps: Background: Go to PhET’s Energy Skate Park (https://phet.colorado.edu/sims/html/energy-skate-park-basics/latest/energy-skate-park-basics_en.html), select the “Friction” run, click “Bar Graph”, and run the simulation a few times to better understand the relationship between potential energy, gravitational energy, and energy dissipated by friction. Determine the problems: What energy transformations take place for a simple pendulum in motion when: there are dissipative forces the mass swings back and forth there is another pendulum in proximity Make a hypothesis: Make a prediction of how you expect each mass and length to change the period.

Test your hypothesis: Build the simple pendulum testing apparatus (see video: I will email you the link ) and record the results for each combination below. How does the mass of a pendulum (of fixed length) affect the time for the oscillation to dampen a specific amount? For a simple pendulum in motion: at which point(s) does the mass have the greatest gravitational potential energy? at which point(s) does it have the greatest kinetic energy? at which point(s) is the velocity of the mass the greatest? For two simple pendulums of the same length and mass: how does the oscillation of one affect the other? how long does it take for one mass to stop? (What is the period of stopping?) For two simple pendulums of the same length but different mass: how does the oscillation of one affect the other? (Start with the larger mass in motion and the smaller at rest. Then repeat, starting with the smaller mass in motion and the larger at rest.) how long does it take for one mass to stop? For two simple pendulums of the same mass but different length: how does the oscillation of one affect the other? (Start with the longer pendulum in motion and the shorter at rest. Then repeat, starting with the shorter pendulum in motion and the longer at rest.) Analyze the results for each case. Draw conclusions: Report the results from your analyses. Comment, in a final paragraph, on your experience with the experiment. How was it? What did you learn about the pendulum? About yourself in the doing of a real experiment?