PURPOSE: To show that the instantaneous velocity of an object executing uniform
circular motion is tangent to the circle, and to
illustrate centripetal force.
DESCRIPTION: Swing the ball around your head in a horizontal plane, demonstrating
uniform circular motion. The required
inward force on the string represents centripetal force. If you release the ball, how will
it tend to move after it is released?
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 at the point where it was released. Let
your students vote before doing the experiment.
EQUIPMENT: Stored in mechanics.
SETUP NOTES: Practice so you do not hit your head with it!