JEE Main 2017PhysicsGravitationMediumMCQ

JEE Main 2017 — Gravitation Question with Solution

JEE Main 2017 (08 Apr Online)

Question

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

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Show full solutionCorrect option: A
Correct answer
A0.63×10-3 rad s-1

Step-by-step explanation

Due to the rotation of the earth,

Changed gravitational acceleration, g′=g-ω2Rcos2⁡θ

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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About this question

This is a previous-year question from JEE Main 2017, covering the Gravitation chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.