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MHT CET202312 May 2023Morning ShiftPhysicsRotational MotionActual

A thin uniform circular disc of mass ' M ' and radius ' R ' is rotating with angular velocity ' ', in a horizontal plane about an axis passing through its centre and perpendicular to its plane. Another disc of same radius but of mass ( M 2 ) is placed gently on the first disc co-axially. The new angular velocity will be

Options

  1. A2 3
  2. B4 5
  3. C5 4
  4. D3 2

Correct answer

A. 2 3

Step-by-step solution

Angular momentum = I By conservation of angular momentum, I ₁ ₁= I ₂ ₂ Here, I₁= M^2 2 , I₂= (M+M / 2) 2 R^2= 3 M^2 4 aligned & MR ^2 2 ₁= 3 MR ^2 4 ₂ & ₂= 2 3 ₁ aligned

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