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COMEDK2023PhysicsRotational Motion

A thin circular ring of mass M and radius R rotates about an axis through its centre and perpendicular to its plane, with a constant angular velocity . Four small spheres each of mass m (negligible radius) are kept gently to the opposite ends of two mutually perpendicular diameters of the ring. The new angular velocity of the ring will be

Options

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

Correct answer

C. ( M M+4 m )

Step-by-step solution

According to conservation of angular momentum, I = constant i.e. we can write, array rlrl I₁ ₁ & =I₂ ₂ & or & M R^2 =(M+4 m) R^2 ₂ & or & ₂ = ( M M+4 m ) & array

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