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JEE Main201912 Jan 2019Morning ShiftPhysicsRotational MotionActual

Let the moment of inertia of a hollow cylinder of length 30 c m (inner radius 10 c m and outer radius 20 c m ), about its axis be I . The radius of a thin cylinder of the same mass such that its moment of inertia about its axis is also I , is:

Options

  1. A16 c m
  2. B14 c m
  3. C12 c m
  4. D18 c m

Correct answer

A. 16 c m

Step-by-step solution

Moment of inertia of a hollow cylinder whose inner radius id r and outer radius is R is given as I = m ( R 2 + r 2 ) 2 m 20 2 + 10 2 2 = m k 2 K = 400 + 100 2 ; K = 250 K = 5 10   c m

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