Consists of a square plexiglas plate, with string attached at it's four corners and tied together to a loop of string.
Demonstrate the action of centripetal force
Place the cup in the center of the Greek Waiter, hold it by the loop of string (you may have to adjust the strings so that the Greek Waiter hangs horizontally) and whirl it around you. If you do this properly (without accelerating the platform too quickly or allowing the string to loose tension) it should be easy to keep the cup of water from spilling. You can whirl it around your head vertically, around your body, or even in a figure eight. Practice at least once before showing in front of a class.
For additional drama you place multiple cups of water on the platform. Be sure to place them so that the waiter is balanced.
This is the same as the demonstration featuring a bucket of water, but the water level is more visible (particularly if you use a clear container with dyed water). You can extend it by placing other objects on the platform with the cup as well.
Demo room information