Mousetrap chain reaction experiment.

Mousetrap chain reaction experiment. See Fig.1. When a uranium 235 atom (or plutonium 239 atom) is hit by a neutron, it can absorb the neutron; then the whole nucleus can split or fission into roughly two equal pieces and in the process two or three neutrons can be released. If the uranium 235 metal is sufficiently purified, the two or three neutrons released can go on to cause additional fissions, so the process multiplies into what can be a self-sustaining chain reaction. The mousetrap chain reaction demonstration mimics with balls what happens in a self-sustaining nuclear chain reaction. A single ball dropped onto an assembly of cocked mousetraps loaded with balls starts a chain reaction that is over in 6-7 seconds. This demo is now 'electronic'. It can be set up quickly ahead of time, without fear that the chain reaction will accidentally go off . See Fig.2. There are 49 modified mousetraps mounted to a board. (The trigger wire and catch of each mousetrap have been removed.) Each mousetrap is manually cocked with the metal striking piece held in place by the flange on a steel rod that fits into an electric solenoid. Two super balls are set on top of the striking piece of each mousetrap, and a Plexiglas cover with a ball-sized hole in the center of the top is lowered over the assembly. Each mousetrap has an associated 'touch-switch' that becomes sensitive when the assembly is turned on. If a switch is touched, the rod in the solenoid retracts, and the mousetrap fires, launching two balls. A ball dropped through the hole in the Plexiglas triggers one mousetrap which launches two balls which hit two other switches which launch four balls and so on...Procedure: Set the traps with the balls. Plug the mousetrap demo into a 120 VAC outlet. Push the 'Arm' button. You now have 2 minutes to drop a ball through a hole in the Plexiglas cover to complete the chain reaction. Product Ref.:Physics For Scientists and Engineers by Giancoli, 2nd ed., p. 995-998