This setup clearly demonstrates simple harmonic motion and the conservation of energy. In simple harmonic motion, pendulum swings evenly from side to side. Use photogate timer to accurately measure the period of the pendulum or the speed of the pendulum bob at the bottom of the swing. The length of the string can be adjusted to measure the change in period. Also see the effect of change in mass on the period. Two pendulum bobs are provided. Photogate Timer is not included.