Who's the Biggest Swinger?

Which will come to rest more quickly, a heavy pendulum or a lighter one? I attempted to answer this question despite my lack of background knowledge. After several trial and error efforts, I still feel that I came up short. I went through a series of failed attempts before coming up with a procedure that seemed to work. I tied two strings, one with the smallest washer and the other with the heaviest. I hung them on a yardstick, which I laid atop the back of two chairs.  In the beginning, the strings were too long so the pendulum knocked into the chairs and tangled together. I tried timing the swings but that took too long, and I soon realized was not necessary. I assumed the flat surface of the yardstick contributed to the wild swinging, so I tied shorter strings and the washers to a dowel. I struggled being able to tell when the pendulum actually stopped. They both continued to sway a tiny bit but the smaller one seemed to stop first but it was close.

                The inconclusive data forced me to try other options. Changing only one variable at a time, I tried using spoons, various string lengths, even taping the string to the dowel instead of tying it. Nothing gave me the definitive answer I was hoping for. I figured I was doing something wrong. At this point I began to seek out help. I returned to the Pendulum Ship from the Newton’s Amusement Land, theme park found in the Walden resource page. It talked about the length of the hanging device being more critical than the mass of the swinging object. I decided to try another approach by attacking my hypothesis from a different angle. I took two identical pair of scissors, and tied them to the dowel using a short string and a longer string. When I pulled the scissors back and released them, the scissors on the shorted string stopped earlier than the other pair. At last I could actually see a result.

                                Help…. found

                I was still unsure of my conclusion and found no information in the text that helped me. I did find using the PhET’s Interactive Simulation website posted by the University of Colorado helpful. I set up a simulation that mirrored my original experiment. I set both pendulums to have an equal length from the top, and used two differently weighted objects. The pair, despite their difference in mass, stopped at the same time. Finally I found a definitive answer to the original question. To satisfy my compulsion to be right, I googled the question to see what I could find. The most helpful information came from Mrsstrasbaughsblogspot.com. She is apparently a teacher earning her master’s degree and took a class last spring similar to ours. Her work was well done and helpful.

                I could never use an activity like this without better closure. Sometimes inquiry is done for the sake of inquiry. This will never work without follow up to assure the students master the concepts.

                                A Scenario…. The Flying Dutchman

                To make this activity more interesting for my students I would propose a scenario as follows. A group of friends go to White Water’s American Adventure Park. They are in line to ride the Flying Dutchman (a pendulum boat ride). Two of the kids start to argue. One of the pair believes that the ride will last longer if there are fewer people on the boat. He said that if there were fewer people, the lower mass would result in the ride stopping slower, thus lasting longer. The other friend said the ride would actually last longer with more people on it. The more mass, the more momentum; therefore, the longer the boat swings back and forth. I would then challenge the students to create an experiment to discover which of the friends was right.  I would then follow up to make sure the concept I wanted them to uncover was understood by them all.

                                What should they learn?

                I have no idea what they should learn from this experiment. I never figured it out on my own. I can only share what I learned from Mrs. Strasbaugh??????

                                To wrap this up….

                It was good for me to experience the frustration of not knowing what I was trying to discover, I guess. It let me see how my students might feel. However, they work in groups and have team mates to bounce ideas off and me as an instructor to provide guidance.