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NEET 2022 (Phase 1) · Moment of Inertia & Radius of Gyration

Moment of Inertia & Radius of Gyration question from NEET 2022 (Phase 1)

Q111NEET 2022 · PHASE 1Easy

Moment of Inertia & Radius of Gyration

The ratio of the radius of gyration of a thin uniform disc about an axis passing through its centre and normal to its plane to the radius of gyration of the disc about its diameter is

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Answer: (b)

  1. Normal axis through centre: I=MR22⇒K1=R2I = \frac{MR^2}{2} \Rightarrow K_1 = \frac{R}{\sqrt{2}}.
  2. About a diameter: I=MR24⇒K2=R2I = \frac{MR^2}{4} \Rightarrow K_2 = \frac{R}{2}.
  3. K1K2=22=2\frac{K_1}{K_2} = \frac{2}{\sqrt{2}} = \sqrt{2}
  4. So the answer is (b) 2:1\sqrt{2} : 1.
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