Lately we've been working with three types of force: gravity, friction, and magnetism. We started an investigation in which we made three pendulums of different lengths. We timed how long each pendulum took to make 10 swings, then looked at our pattern. For our pendulum with a string 10cm long, it took 5 seconds to swing 10 times. For our pendulum with a string of 20cm long, it took 6 seconds. Our pendulum with a string of 30cm long took 7 seconds to swing 10 times. We then predicted how long it would take a pendulum with strings of 40cm and 50cm to swing 10 times.
We discussed the forces involved in our experiment. We talked about the gravitational pull, which was responsible for making our pendulum fall. We also discussed the friction of the air rubbing against the string, which was responsible for slowing down the pendulum to an eventual stop. There is also friction found in the string rubbing against the pencil. This, too, helps slow our pendulum's swing.
