Question

A circular disk of moment of inertia I_t is rotating in a horizontal plane, about its symmetry axis, with a constant angular speed ω_i. Another disk of moment of inertia I_b is dropped coaxially onto the rotating disk. Initially the second disk has zero angular speed. Eventually both the disks rotate with a constant angular speed ω_f The energy lost by the initially rotating disc to friction is

Answer 1

Correct option (d)

Explanation:

As no external torque is applied to the system, the angular momentum of the system remains conserved.

:. L_i = L_f

According to given problem,