Medium MCQ +4 / -1 PYQ · JEE Mains 2021

If the angular velocity of earth's spin is increased such that the bodies at the equator start floating, the duration of the day would be approximately : [Take g = 10 ms$-$2, the radius of earth, R = 6400 $\times$ 103 m, Take $\pi$ = 3.14]

  1. A 84 minutes Correct answer
  2. B 1200 minutes
  3. C 60 minutes
  4. D does not change

Solution

For objects to float<br><br>mg = 2$\omega$<sup>2</sup>R<br><br>$\omega$ = angular velocity of earth.<br><br>R = Radius of earth<br><br>$\omega = \sqrt {{g \over R}}$ ..... (1)<br><br>Duration of day = T<br><br>$T = {{2\pi } \over \omega }$ ..... (2)<br><br>$\Rightarrow T = 2\pi \sqrt {{R \over g}}$<br><br>$= 2\pi \sqrt {{{6400 \times {{10}^3}} \over {10}}}$<br><br>$\Rightarrow {T \over {60}}$ = 83.775 minutes<br><br>$\simeq$ 84 minuites

About this question

Subject: Physics · Chapter: Gravitation · Topic: Kepler's Laws

This question is part of PrepWiser's free JEE Main question bank. 129 more solved questions on Gravitation are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →