Pendulum Swings

Prior to beginning this experiment, I hypothesized that the lighter pendulum would come to rest more quickly. My hypothesis was based on my prior knowledge of gravity, mass, and inertia. In beginning the experiment, I tied the string to the pencil before taping the pencil to the countertop as this was a constant since I did not untie the string from the pencil for the duration of the experiment. Taping the pencil to the countertop allowed free oscillation of the pendulum. Next, I attached the other end of the string to the smaller washer, which had a quarter inch diameter in length. I dropped the pendulum from the lowest point of the pencil that was hanging off of the countertop and allowed the pendulum to swing for twenty five seconds. The same procedure was repeated for the next pendulum, which was made using a washer with a half inch diameter. Although the mass of the washers were different, both pendulums completed thirteen rounds. The release points of the pendulums, the length of the string, and the amount of time allotted for the swings were constants. My hypothesis was correct since the lighter pendulum came to rest first.

My students would probably hypothesize that the heavier pendulum would come to rest quicker after completing the “Falling Bodies Experiment” last week and noticed that the heavier objects reached the floor first. Challenges came when I tried to accurately perform the experiment using the same release height and force for both pendulums. Students would be provided the opportunity to measure their strings, discuss why their data differs from their classmates, and debate about the effects of the washer sizes. Students will also have the opportunity to drop their pendulums from whatever reasonable height they choose. “When students gain experience with problem solving, they have the potential to invent new ways of doing things”. Students may be challenged with releasing their pendulums at the same height or accurately starting and stopping the stopwatch.