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MHT CET 2021 (23 Sep, Shift 2) · Acceleration Due to Gravity

Acceleration Due to Gravity question from MHT CET 2021 (23 Sep, Shift 2)

Q100MHT CET 2021 · 23 SEP · SHIFT 2Difficult

Acceleration Due to Gravity

A body of mass 'M' and radius 'R', situated on the surface of the earth becomes weightless at its equator when the rotational kinetic energy of the earth reaches a critical value 'K'. The value of 'K' is given by [Assume the earth as a solid sphere, g = gravitational acceleration on the earth's surfacde]

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Answer: (d)

  1. Here MM and RR are the earth's mass and radius.
  2. Weightless at equator: ω2R=g⇒ω2=gR\omega^2 R = g \Rightarrow \omega^2 = \frac{g}{R}
  3. K=12Iω2=12⋅25MR2⋅gRK = \frac{1}{2}I\omega^2 = \frac{1}{2} \cdot \frac{2}{5}MR^2 \cdot \frac{g}{R}
  4. K=15MgRK = \frac{1}{5}MgR, so the answer is (d).
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