Table of Mechanics Demonstration List of Mechanics Equipment & Supplies Lecture Demonstrations

# Ball on a String, 1D50.10

Topic and Concept:

Location:

Abstract:

A tennis ball tied to a sting is whirled around in a vertical circle by hand.

 Equipment Location ID Number Tennis Ball w/Attached String (2) ME, Bay A2, Shelf #1 Also can be found with in room tact cabinet

Important Setup Notes:

• Please use the Tennis Ball ones only! The brass and wood balls, are for hand-held pendulums and can be dented if smacked around.

Setup and Procedure:

1. Hold the string in hand securely.
2. Swing the ball into a circular trajectory.

Cautions, Warnings, or Safety Concerns:

• N/A

Discussion:

When swinging the ball, which gives it momentum, the ball is unable to travel in a straight line. The string puts a tension on the ball causing it to arc around. In other words, the ball is put into a circular trajectory due to the centripetal force being provided by the tension in the string which is proportional to the tangential speed of the ball. To prove the is a central force to the audience, just simply let go of the string. The ball will then travel tangent to the circular trajectory it was on.

Videos:

References:

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