Physics Demo Number: 194
Approximate
Run Time: 5 min
Vortex Generator
Demo Description
A wooden box has one face replaced by a thick rubber sheet.
The face opposite this one has an 8 cm or so round hole in its center.
Holding the wooden box in one hand and rapping sharply on the rubber sheet with the other hand, gives rise to a powerful vortex ring emerging from the hole and propagating across the lecture hall.
Scientific Principles
Vortex rings can carry surprising amounts of energy and momentum through the room air .
Equipment
- A special wooden box is fitted with a rubber sheet face and a wood face with a round hole.
Equipment Location
- The box lives in [F-3-6].
Instructions
The three pictures show front and back views of the box.
Holding the wooden box in one hand and rapping sharply on the rubber sheet with the other hand, gives rise to a powerful vortex ring emerging from the hole.
The ring propagates across the lecture hall and can be made to move objects or blow out candles , with some practice in aiming the box properly.
