Does Mass Matter?

When choosing a guided inquiry experiment to complete, I chose the activity    that I knew the least about. I was very interested in determining if the mass of a pendulum would affect the pendulum’s swing frequency. I have always been fascinated by my grandparent’s old pendulum clock. I took this opportunity to find out more about the process of these amazing tools.             In completing this experiment, I created a pendulum using a swing, spool of threat, steel washers, and a stop watch. Using the string and spool I created a simple pendulum and used the stop watch. I started the pendulum and documented how long it took for the pendulum to come to a complete stop. I then added 22 grams of washers to the top of the pendulum. It was at this point that my personal hypothesis began to collide.
            Before completing the latter part of the experiment, I had hypothesized what I thought would happen. I hade many mixed thoughts about the specifics of this experiment. I knew that adding washers to the spool or pendulum would add more mass to the pendulum, but it would also add to the air resistance that the pendulum was facing. In addition to these thoughts, I also had in mind what Galileo discovered in the late 1500’s and the early 1600’s. Galileo determined that the velocity of a falling object does not depend on it’s weight and any differences in a falling objects is explainable by air resistance (Tilley, Enger, Ross, 2008). With all this information in mind, I hypothesized that the bob’s mass would not affect it’s swing frequency.
            After completing this experiment, I discover that my hypothesis was correct. Adding more mass to the bob does make the bob itself heavier, but it also increased the amount of gravitational pull on the bob. I hypothesis that when the bob is in the upswing, gravity is acting upon the bob in proportion to the bob’s weight.
            To replicate this experiment, I could use the same materials in my classroom. I would have my students place their reading book on the side of their desk and hang the pendulum. We could use the stop watches that we use for our reading fluency to time the pendulums. To enrich this experiment, students could shorten their strings and see how the lenght affects the results. Students could also link this new knowledge to how the swings on their playground work.