Physics Dept. Demonstration Manual

DRD01 - Moment of Inertia, Magic Batons

Objective:

To demonstrate that the moment of inertia of an object depends on the mass distribution relative to the axis of rotation.

 
Apparatus:  
  • two batons
The batons each have a mass of about 1.5 Kg, but one has most of its mass near the center, while the other has the mass mostly concentrated in the ends. The tape band marks the center of the batons. It is intended that the batons be oscillated back and forth about the marked center.



Method:

An effective demonstration method is to have a student grip the center band of the end weighed baton while the instructor grips the center of the center weighted baton. Ask the student to oscillate his/her baton in time with the instructor's oscillation of the center weighted baton. As the instructor increases speed, the student is unable to keep up.