Transcript:

Let's do a cool experiment in the kitchen. Take a boiled egg and a raw egg, and spin both of them on the countertop and briefly stop both of them. The raw egg will start moving after stopping. The fully boiled egg will not.

This is because of conservation of angular momentum. The liquid inside the raw egg still is spinning even though the shell is stopped.

The same technique is used by dancers and ballet dancers. When they are spinning, you notice their head does not spin continuously. Their head is stationary, and as the body spins, at the end of the body spin, the head moves very fast. So it's a start-and-stop motion. Notice their head. It's a start-and-stop motion.

This is because the dancer doesn't want to get dizzy, and the only way for the dancer to not get dizzy is to rapidly start and stop the head movement so that the fluid in the inner ear does not have time to develop momentum. If the fluid in the inner ear develops momentum, the dancer will get dizzy.

So, conservation of angular momentum is fundamental to very good dancing.