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JEE Main 2023 (1 Feb, Shift 2) · Moment of Inertia & Radius of Gyration

Moment of Inertia & Radius of Gyration question from JEE Main 2023 (1 Feb, Shift 2)

Q90JEE Main 2023 · 1 FEB · SHIFT 2Easy

Moment of Inertia & Radius of Gyration

Moment of inertia of a disc of mass 'MM' and radius 'RR' about any of its diameter is MR24\frac{MR^2}{4}. The moment of inertia of this disc about an axis normal to the disc and passing through a point on its edge will be, x2\frac{x}{2} MR22. The value of xx is ___________.

Numerical answer type. Work it out, then open the answer.

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Answer: 3

  1. Perpendicular axis theorem: Icm=2×MR24=MR22I_{cm} = 2\times\frac{MR^2}{4} = \frac{MR^2}{2}.
  2. Parallel axis to the edge: I=MR22+MR2=32MR2I = \frac{MR^2}{2} + MR^2 = \frac{3}{2}MR^2.
  3. Comparing with x2MR2\frac{x}{2}MR^2: x=3x = 3.
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