Mass On String - Orbits With Varying Radius

Purpose

To illustrate conservation of angular momentum.

Equipment

Ball of string and metal tube.

Images

Description

Rotate the mass on the string with the central end of the string passing through the tubular metal collar.Pulling the string decreases the radius of the ball, thus decreasing the moment of inertia and increasing the angular speed of the ball.

References

John H. Walters, Jr., Centripetal Force Apparatus, AJP 29, 212, (1961).