egg test
How can you tell a hard boiled egg from an uncooked one
without breaking the shell? Spin each egg on a smooth flat
surface. The hard boiled egg will spin much longer.
When you spin the raw egg, you turn the shell but the inertia
of the liquid contents keeps the contents from turning much.
The shell is moving rapidly and the contents are moving
slowly. When you release the shell, the shell is quickly
slowed down by the liquid.