Projection of Uniform Circular Motion and Simple Harmonic Motion of a Pendulum

Set the pool ball pendulum length to 35.5 cm.  Place the horizontal-plane rotating motor underneath the pendulum.  Place the illuminating slide projector about a meter away and project the images of the swinging pendulum and rotating ball on a wall. Start the pendulum so that its swing is in phase with the driven ball.

Uniform Circular Motion describes the movement of an object traveling a circular path with constant speed. The one-dimensional projection of this motion can be described as simple harmonic motion.

A point P moving on a circular path with a constant angular velocity ω is undergoing uniform circular motion. Its projection on the x-axis undergoes simple harmonic motion. This can be compared with the projection of the linear horizontal motion of a pendulum.