question_answer

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 J, is- [JEE Main 12-Jan-2019 Morning]

A)   14 cm           

B)   16 cm

C)   12 cm           

D)        18 cm

Correct Answer: B

Solution :

[b]