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Question: Answered & Verified by Expert
If the Earth has no rotational motion, the weight of a person on the equator is W. Determine the speed with which the earth would have to rotate about its axis so that the person at the equator will weigh 34 W. The radius of the Earth is 6400 km and g=10 m s-2
PhysicsGravitationJEE Main
Options:
  • A 0.63×10-3 rad s-1
  • B 0.28×10-3 rad s-1
  • C 1.1×10-3 rad s-1
  • D 0.83×10-3 rad s-1
Solution:
1599 Upvotes Verified Answer
The correct answer is: 0.63×10-3 rad s-1
Due to the rotation of the earth,

Changed gravitational acceleration, g=g-ω2Rcos2θ

At the equator, angle of inclination, θ=0 

3g4=g-ω2R

w2R=g4

w= g4R

= 104×6400×103

=12×8×100

=11600=116×10-2=0.6×10-3 rad s-1.

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