NEET2010PhysicsRotational MotionActual
A circular disk of moment of inertia I_t is rotating in a horizontal plane, about its symmetry axis, with a constant angular speed _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 _ f . The energy lost by the initially rotating disc due to friction is
Options
- A1 2 I _ b ^2 ( I _ t + I _ b ) _ i ^2
- B1 2 I _ t ^2 ( I _ t + I _ b ) _ i ^2
- C1 2 I _ b - I _ t ( I _ t + I _ b ) _ i ^2
- D1 2 I _ b I _ t ( L _ t + I _ b ) _ i ^2
Correct answer
D. 1 2 I _ b I _ t ( L _ t + I _ b ) _ i ^2
Step-by-step solution
Loss of energy, E = 1 2 I _ t _ i ^2- 1 2 I _ t ^2 _ i ^2 ( I _ t + I _ b ) = 1 2 I _ b I _ t _ i ^2 ( I _ t + I _ b )