Periodic Wave Generated by a Pendulum Sandglass

time

speed

3

5

10

This Demonstration shows a wave generated by a pendulum sandglass. The wave is well approximated as a sinusoid, but not exactly since this is a spherical pendulum. The pendulum consists of a hollow tube with sand running down from a funnel at the top. It is assumed that the pendulum's mass and period are constant and that frictional losses can be neglected.