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MHT CET202124 Sep 2021Morning ShiftPhysicsRotational MotionActual

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

Options

  1. A1 2 MgR
  2. B1 3 MgR
  3. C1 4 MgR
  4. D1 5 MgR

Correct answer

D. 1 5 MgR

Step-by-step solution

A body will become weightless at equator if R ^2=g or ^2= g R Kinetic energy of the earth, K = 1 2 I ^2 For a solid sphere, I = 2 5 MR ^2 (M is mass of the earth) K = 1 2 2 5 MR ^2 g R = 1 5 MgR

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