Cat & Turntable: Angular Velocity Comparison?

[physgirl]

If there's a cat and a turntable both of same mass each... and the cat starts walking around the edge of the turntable which is initially at rest, how would the angular velocity of the two objects compare? Would the cat move at all since it has the same mass as the turntable and momentum has to be conserved??

 

[OlderDan]

Yes, the cat would have to move to conserve angular momentum. Can you show why? Assume the turntable is a disk of radius R and work it out.