JEE Main2011PhysicsRotational MotionActual
A pulley of radius 2 ~m is rotated about its axis by a force F = (20 t -5 t ^2 ) Newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation made by the pulley before its direction of motion if reversed, is :
Options
- Amore than 3 but less than 6
- Bmore than 6 but less than 9
- Cmore than 9
- Dless than 3
Correct answer
A. more than 3 but less than 6
Step-by-step solution
r F = l 2 (20 t -5 t ^2 )=10 =4 t - t ^2 d dt =4 t - t ^2 ~d = (4 t ^2- t ^2 ) dt =2 t ^2- t ^3 3 (on integration) =0 t =6 ~s