Re: Why does a hard-boiled egg spin faster and longer than a raw egg

It is my educated hypothesis that centripital force and moment of inertia are involved.

As the raw egg spins, the more dense mass is drawn away from the center and toward the edge (centripital force; like going around a turn in a car). This causes a higher moment of inertia and a slower spin. This does not occur in the boiled egg.

For example, ice skaters start spinning w/ their arms out. They speed up when drawing their mass to the center; thus changing their moment of inertia. There is a physics demo where you hold 10 lb. weights while spinning on a swivel stool. When you pull the weights in, you go fast and vica versa.

Greg Corder

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Admin note:
Mukund V. Karwe adds the following:

Hardboiled egg being a solid mass has a higher angular moment of inertia as compared to a raw egg which has thick liquidy stuff in it. The liquid rotates when the egg is rotated but not as fast as a solid egg. Hence the hard-boiled egg spins for a longer time. I don't think it spins faster.

-MVK