Any suggestions for a cool physics demo?

Question

We were asked to do an exhibit that is interactive and interesting. Anything about physics! :D

Answer 1

The mentos and diet coke trick :)

Answer 2

Here's one that we did in college physics class. Get a bowling ball, drill a hole through it and put a big eye bolt in (make sure it's securely bolted in... the eye bolt should pass entirely through the center of the bowling ball with washers and nuts on the top and bottom). Tie a rope or chain to the eye bolt, suspend it from the ceiling so it doesn't quite touch the floor.

Have your victim stand off to one side. Bring the ball up (keeping the line taut) until it's touching the person's nose. Let go so it swings (like a pendulum). Now comes the fun part... as the ball comes flying back up towards them, see if they jump out of the way.

The experiment shows the second law of thermodynamics. There is no way the ball can come back up as far as it was in the first place (friction takes some energy out of the system).

Answer 3

It's pretty simple, but try spinning someone on a rotating chair and having them move their legs and arms in and out to change their rotational speed. Just be careful that you start them spinning with their legs and arms tucked in, otherwise they may pick up too much speed when they pull them in, and fall off the chair.

Another fun one (but with more prep) is to take a table and drill a hole in it, then run a string through and attach a weight to each end. Make sure friction between the upper weight and table is minimized (some sort of grease is probably best), then give the upper weight some angular momentum. The force of gravity on the lower weight will pull the upper weight closer and closer to the center--until it reverses direction and starts heading back out.

Answer 4

People always love anything you can do with liquid nitrogen if you have access to it. Double pendulums are interesting too. For large oscillations, you can demo chaos ( http://lecturedemo.ph.unimelb.edu.au/mechanics/chaos/chaotic_double_pendulum ). To demo energy transfer, hang a large weight from a string. From the bottom of the large weight, hang a tiny weight with about the same length of string. If you tap the big weight slightly, the energy will transfer and cause the little weight to go crazy.

Answer 5

Have students bring their skateboards (they love this). Take the class outside and have the students try to skate on different surfaces. Have them skate from one surface to another - e.g. asphalt to grass. This will give you and the class many topics to discuss.