JEE Mains · Physics · STD 11 - Gravitation
- JEE Mains 2021
- Medium
- Numerical
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 ........ minutes (Take : \(g =10 \,ms ^{-2},\) the radius of earth, \(R =6400 \times 10^{3}\, m ,\) Take \(\left.\pi=3.14\right)\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(D) \(84\)
Step-by-step Solution
Detailed explanation
For objects to float
\(mg = m \omega^{2} R\)
\(\omega=\) angular velocity of earth.
\(R =\) Radius of earth
\(\omega=\sqrt{\frac{g}{R}}\)
Duration of day \(= T\)
\(T =\frac{2 \pi}{\omega}\)
\(\Rightarrow T =2 \pi \sqrt{\frac{ R }{ g }}\)
\(=2 \pi \sqrt{\frac{6400 \times 10^{3}}{10}}\)
\(\Rightarrow \frac{ T }{60}=83.775\) minutes
\(\simeq 84\) minutes
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