1D50.40-Pail of Water


Video: Watch this demo | Demo #2

Description: This demo shows how centripetal forces relate to the inertia of the object that is being rotated.

Note: If you go too slow, the water will fall out.


  • Metal pale with rope tied to the handle
  • Water

Setup Procedure:

  1. Check to make sure strings are securely attached.
  2. Can fill the pale ahead of time, or leave for professor to fill in class. Ask what is preferred.

Demonstration Procedure:

  1. Carefully start swinging the water-filled pail.
  2. When ready, swing the pail in a full circle while quickly reaching a stable spinning speed.
  3. When stopping, carefully bring the pail out of rotation so as to avoid spilling water all over the floor. (You have to use some physics intuition to get the hang of this!)