Tennis Ball Cannon
Brief Description
When the cannon is fired, there is a significant force being applied to the tennis ball. Because of this, there is an equal force also applied to the cannon. This can be seen as the tennis ball will eject forward and the cannon will roll backwards.
Materials
Tennis ball cannon
Tennis ball
Lighter
95% Ethyl alcohol
Performing the demo
Fill the back of the cannon with a tablespoon or so of alcohol and swirl the cannon around to coat the inside. Push the tennis ball slightly into the front of the cannon. Let the cannon sit for a couple minutes to let the alcohol vapor build up.
Face the cannon towards a wall, then put the flame from the lighter over the hole on top of the cannon.
Safety
Do not fire the cannon when anyone is in front of or behind it.