Let the moment of inertia of a hollow cylinder of length 30   c m (inner radius 10   c m and outer…

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:
  1. 16 cm
  2. 14 cm
  3. 12 cm
  4. 18 cm

Solution

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=510 cm

Asked in: JEE Main 2019 (12 Jan Shift 1)

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