PURPOSE: To illustrate the complex motion resulting from addition of two angular velocities.

DESCRIPTION: The rotating disc with the lamp attached to its perimeter can spin in its mount on low-friction bearings. Simultaneously, the mount can be rotated by hand. As the light bulb rotates about the two axes it traces out a complicated motion which is the sum of two angular velocities.

SUGGESTIONS: Requires darkened room.

REFERENCES: (PIRA 1D10.40)

EQUIPMENT: Hand rotator, rotating disc with light, as photographed.

SETUP TIME: None.