Model of planetary path
A demonstration of epicyclic motion.
Apparatus and materials
Small DC motor on a base plate
Battery, 1.5 V
Health & Safety and Technical notes
Make sure that the polystyrene ball is firmly fixed and the sharp point is protected.
Attach the motor base plate to the turntable. When the battery is connected it drives the motor, which rotates a polystyrene sphere in a small circle as shown. At the same time rotate the turntable slowly by hand.
The epicyclic motion of the small sphere can be observed by the class looking edgewise at the model.
This experiment was safety-checked in April 2007