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Manipal MET2013PhysicsRotational Motion

A circular disc is rotating with angular velocity . If a man standing at the edge of the disc walks towards its centre then the angular velocity of the disc will

Options

  1. Adecraese
  2. Bincrease
  3. Cbe halved
  4. Dnot change

Correct answer

B. increase

Step-by-step solution

When no external force acts on a body its angular moment remains conserved. From law of conservation of angular momentum, we have J=l = constant where / is moment of inertia of the body and is angular velocity. Also I= 1 2 M R^2 (for disc) where M is mass and R is radius of disc. J= 1 2 M R^2 = constant Since, man moves towards the centre of the disc, distance of mass distribution R decreases hence, increases.

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