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MHT CET 2026 (13 Apr, Shift 2) · Moment of Inertia & Radius of Gyration

Moment of Inertia & Radius of Gyration question from MHT CET 2026 (13 Apr, Shift 2)

Q28MHT CET 2026 · 13 APR · SHIFT 2Medium

Moment of Inertia & Radius of Gyration

A thin uniform rod of length 22 m cross-sectional area 'A' and density 'd' is rotated about an axis passing through the centre and perpendicular to its length with angular velocity ω\omega. If the value of ω\omega in terms of its rotational kinetic energy EE is (αE/Ad)1/2(\alpha E/Ad)^{1/2}, then the value of α\alpha is

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Answer: (b)

  1. Mass M=A⋅2⋅d=2AdM = A \cdot 2 \cdot d = 2Ad, I=ML212=2Ad⋅412=2Ad3I = \frac{ML^2}{12} = \frac{2Ad \cdot 4}{12} = \frac{2Ad}{3}.
  2. E=12Iω2=Ad ω23E = \frac{1}{2}I\omega^2 = \frac{Ad\,\omega^2}{3}
  3. ω=(3EAd)1/2\omega = \left(\frac{3E}{Ad}\right)^{1/2}, so α=3\alpha = 3.
  4. So the answer is (b) 3.
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