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Question: Answered & Verified by Expert
Two rings of radius 'R' and 'nR' made of same material have the ratio of moment of inertia about an axis passing through its centre and perpendicular to the plane as $1: 8 .$ The value of 'n' is (mass per unit length is constant)
PhysicsRotational MotionMHT CETMHT CET 2020 (14 Oct Shift 1)
Options:
  • A 1
  • B 3
  • C 4
  • D 2
Solution:
2355 Upvotes Verified Answer
The correct answer is: 2
$\begin{array}{l}
I_{1}=M R^{2}, I_{2}=(n M)(n R)^{2}=n^{3} m R^{2} \\
\therefore \frac{I_{1}}{I_{2}}=\frac{1}{n^{3}}=\frac{1}{8} \\
\therefore n=2
\end{array}$

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