Purpose:Show that the instantaneous velocity of an object executing uniform circular motion is tangent to the circle.
Description:A marble is rolled around the inside of the circular band on an overhead projector. 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.
A transparent sheet is available with an outline of the circle and various possible paths. This can be used to challenge the students to guess the outcome of the experiment before performing it.