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MHT CET 2021 (20 Sep, Shift 2) · Moment of Inertia & Radius of Gyration

Moment of Inertia & Radius of Gyration question from MHT CET 2021 (20 Sep, Shift 2)

Q120MHT CET 2021 · 20 SEP · SHIFT 2Easy

Moment of Inertia & Radius of Gyration

The ratio of radii of gyration of a circular ring and circular disc of the same mass and radius, about an axis passing through their centres and perpendicular to their planes is

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Answer: (c)

  1. Ring: I=MR2⇒Kr=RI = MR^2 \Rightarrow K_r = R.
  2. Disc: I=MR22⇒Kd=R2I = \frac{MR^2}{2} \Rightarrow K_d = \frac{R}{\sqrt{2}}.
  3. Kr:Kd=1:12=2:1K_r : K_d = 1 : \frac{1}{\sqrt{2}} = \sqrt{2} : 1
  4. So the answer is (c) 2:1\sqrt{2} : 1.
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