Question
A circular disk of moment of inertia It is rotating in a horizontal plane, about its symmetry axis, with a constant angular speed.
Another disk of moment of inertia Ib is dropped coaxially onto the rotating disk. Initially, the second disk has zero angular speed. Eventually, both the disks rotate with constant angular speed.
The energy lost by the initially rotating disc due to friction is
Solution
D.
Loss of energy, 
