2C20.30 Floating Ball


Bernoulli's principle


A ball or other object is suspended in the air stream provided by a reversed vacuum cleaner according to the Bernoulli's principle.



  • [1] Reversed vacuum cleaner
  • [1] 2 L plastic bottle with a small amount of water inside
  • Styrofoam and plastic balls of various sizes

Classroom Assembly

  1. Plug in the reversed vacuum.

Important Notes

  • Ensure demo will not be placed beneath low-hanging lights or low ceiling.


  1. Place a ball on top of the vacuum cleaner.
  2. Turn on the vacuum. Notice that the ball is floating in the air.
  3. Replace the ball with a different-sized ball or a plastic bottle.
  4. Try floating two styrofoam balls at once. This should be possible with two large ones.
  5. Catch the floating object(s) mid-air before turning off the vacuum.


Additional Resources


  • PIRA 2C20.30


  • Don't attempt this at home!

Last revised

  • 2020


  • The small amount of water in the 2 L bottle is to reduce tumbling

Related AV

Related demos

  • Flying Toilet Paper
  • Funnel and Ball

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.