JEE Main202126 Feb 2021Evening ShiftPhysicsRotational MotionActual
A cord is wound round the circumference of wheel of radius r , The axis of the wheel is horizontal and the moment of inertia about it is I . A weight m g is attached to the cord at the end. The weight falls from rest. After falling through a distance h , the square of angular velocity of wheel will be
Options
- A2 m g h I + m r 2
- B2 m g h I + 2 m r 2
- C2 g h
- D2 g h I + m r 2
Correct answer
A. 2 m g h I + m r 2
Step-by-step solution
m g h = 1 2 I ω 2 + 1 2 m v 2 v = ω r m g h = 1 2 I ω 2 + 1 2   m ω 2 r 2 2 m g h I + m r 2 = ω 2