Trajectory From Circular Orbit

Purpose

To show that the instantaneous velocity of an object executing uniform circular motion is tangent to the circle.

Equipment

Circular band and pool ball.

Suggestions

Suggest three possibilities: (1) the ball will tend to move away from the center of the circle, (2) the ball will tend to continue to move around in a circle, or(3) the ball will move away tangent to the circle. Let your students vote before doing the exp

Images

d1-32

Description

A pool ball is rolled around the inside of the circular band. When the ball leaves the end of the circular segment it will travel in the direction tangent to the circle at the point where it leaves.

References

Jonathan Mitschele, A New Use for an Old Pickle Bucket, TPT 32, 252-253 (1994). Harry Rheam, Tricks of the Trade: Centripetal Force on an Overhead Projector, TPT 33, 182 (1995).