1D50.10 Ball on a String

Concepts

Circular motion, instantaneous velocity of an object moving in a circle.

Overview

Swing the ball on the string to show circular motion. Release the ball to show the instantaneous velocity of the ball. Note: this demonstration is appropriate for large lecture halls.

Details

Equipment

  • [1] Ball on a string

Important Notes

  • When demonstrating circular motion, swing the ball in a vertical path to increase visibility.
  • When demonstrating the instantaneous velocity of an object moving in a circle, swing the ball in a horizontal path to avoid complications due to gravity (the ball will travel along a parabolic path when released during a vertical swing whereas it will travel along a roughly horizontal path when released during a horizontal swing).
  • It is easy to hit a student when releasing the ball. Practice this demonstration in advance.

Script

To show circular motion:

  1. Hold onto the end of the string.
  2. Swing the ball in a vertical path.

To show the instantaneous velocity of an object moving in a circle:

  1. Hold onto the end of the string.
  2. Swing the ball in a horizontal path.
  3. Release the string. The ball will continue along a roughly horizontal path (the ball will fall, but it is not as obvious as when the ball is released in a vertical swing).

 

Additional Resources

References

  • PIRA 1D50.10

Disclaimer

  • Don't attempt this at home!

Last revised

  • 2018

Technicals

  • A string was threaded through a ball.

Related AV

Related demos

If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.