Question

Why is angular momentum of the disk itself conserved?

So a ladybug is standing on a rotating disk that is spinning counterclockwise. Then it starts walking in a circular path in the direction of the disks's rotation? Does the magnitude of the angular momentum of the disk alone increase, decrease, or stay the same? My teacher says it stays the same but I don't understand how. Can anyone help? Thanks!

Answer 1

I would say that the angular momentum of the disk alone decreases.

Explanation:

There is a system here. The angular momentum of the disk+ladybug system must be conserved. The contribution to the system momentum of the ladybug itself increases when the ladybug starts walking. Therefore the momentum of the disk itself must decrease.

I hope this helps,
Steve