1. The problem statement, all variables and given/known data A solid rubber wheel of radius [itex]R[/itex] and mass [itex]M[/itex] rotates with angular veloctiy [itex]\omega_0[/itex] about a frictionless pivot. A second rubber wheel of radius [itex]r[/itex] and mass [itex]m[/itex], also mounted on a frictionless pivot, is brought into contact with it. What is the final angular velocity of the first wheel? 2. Relevant equations Conservation of angular momentum? 3. The attempt at a solution I'm not entirely sure what this question is asking. I think it means that the wheels are held together and you must find the final angular velocity of the first one. If that is the case then you would use the relations [itex]R\omega = r\omega'[/itex] and [itex] I\omega_0 = I\omega + I'\omega' [/itex], noting that the initially stationary wheel would have negative angular velocity. Is this the way to do it?