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MHT CET202014 Oct 2020Evening ShiftPhysicsRotational MotionActual

A thin circular ring of mass ' M ^ and radius ' R ^ is rotating about a transverse axis passing through its centre with constant angular velocity ' '. Two objects each of mass 'm' are attached gently to the opposite ends of a diameter of the ring. What is the new angular velocity?

Options

  1. AM M+2 m
  2. BM( ) M+m
  3. C(M+2 m) M
  4. D( M -2 ~m ) M +2 ~m

Correct answer

A. M M+2 m

Step-by-step solution

Initial angular momentum of the ring =I =M R² If the new angular velocity is ^ then the final angular momentum =I^ ^ where I^ =M R²+2 m R²=(M+2 m) R² . By law of conservation of momentum array c I ^ ^ = I ( M +2 ~m ) R ² ^ ^ = M M +2 ~m array = MR ²

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