Exhibit: Pop Gun

The falling bowling ball forces the air trapped in the big tube along the smaller tube. The air pressure rises forcing the tennis ball out at speed, giving a nice pop! This is an example of a controlled mechanical explosion. An explosion is a rapid release of energy.

This exhibit illustrates the effects of pressurising gases, forces and the conversion of potential energy from gases into other forms of energy. The exhibit consists of a large tube, which contains a bowling ball at one end; this connects to a narrower tube containing a tennis ball. A rope pulled by the visitor lifts the bowling ball up. When the rope is released, air trapped under the ball is forced down into the narrower tube, where it becomes highly compressed (squashed). The pressure of air in the tube sends the tennis ball shooting high into the air, once the pressure is high enough to overcome the weight of the ball. A conical net funnels the falling tennis ball back into the tube for the next shot.