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JEE Main 2006 (AIEEE) · Moment of Inertia & Radius of Gyration

Moment of Inertia & Radius of Gyration question from JEE Main 2006 (AIEEE)

Q190JEE Main 2006 · AIEEEEasy

Moment of Inertia & Radius of Gyration

Four point masses, each of value m,m, are placed at the corners of a square ABCDABCD of side ll. The moment of inertia of this system about an axis passing through AA and parallel to BDBD is

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Answer: (c)

  1. The axis through AA parallel to BDBD is at distance l2\frac{l}{\sqrt{2}} from BB and DD, and 2 l\sqrt{2}\,l from CC; AA is on it.
  2. I=2m⋅l22+m⋅2l2I = 2m\cdot\frac{l^2}{2} + m\cdot 2l^2
  3. I=ml2+2ml2=3ml2I = ml^2 + 2ml^2 = 3ml^2
  4. So the answer is (c) 3ml23ml^2.
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