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Question: Answered & Verified by Expert
Let the moment of inertia of a hollow cylinder of length 30 cm (inner radius 10 cm and outer radius 20 cm ), 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:
PhysicsRotational MotionJEE MainJEE Main 2019 (12 Jan Shift 1)
Options:
  • A 16 cm
  • B 14 cm
  • C 12 cm
  • D 18 cm
Solution:
1590 Upvotes Verified Answer
The correct answer is: 16 cm

Moment of inertia of a hollow cylinder whose inner radius id r and outer radius is R is given as 

I=m(R2+r2)2

m202+1022=mk2

K=400+1002; K=250

K=510cm

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