A circular, solid disc of radius R and mass 2M is rotating with angular velocity w. A second disc of radius R and mass M is dropped onto the rotating disc, and the two slide against each other until they reach the same final angular velocity. (a) What is the final angular velocity of the discs? (b) What percentage of the initial KE was lost during the collision?

A circular, solid disc of radius R and mass 2M is rotating with angular velocity w. A second disc of radius R and mass M is dropped onto the rotating disc, and the two slide against each other until they reach the same final angular velocity. (a) What is the final angular velocity of the discs? (b) What percentage of the initial KE was lost during the collision?