Q. A disc of moment of inertia
′I′1 is rotating in horizontal plane about an axis passing through a centre and perpendicular to its plane with constant angular speed
′ω′1. Another disc of moment of inertia
′I′2 having zero angular speed is placed coaxially on a rotating disc. Now both the discs are rotating with constant angular speed
′ω′2. The energy lost by the initial rotating disc is
- 12[I1I2I1−I2]ω21
- 12[I1+I2I1I2]ω21
- 12[I1−I2I1I2]ω21
- 12[I1I2I1+I2]ω21