JEE Mains · Physics · STD 11 - Gravitation
- JEE Mains 2022
- Medium
- MCQ
The approximate height from the surface of earth at which the weight of the body becomes \(\frac{1}{3}\) of its weight on the surface of earth is \(..........km\) : [Radius of earth \(R =6400 \,km\) and \(\sqrt{3}=1.732]\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(4685\)
Step-by-step Solution
Detailed explanation
\(Mg ^{\prime}=\frac{ M }{3}\, g\)
\(g ^{\prime}=\frac{ g }{3}\)
\(g^{\prime}=g\left(\frac{R}{R+h}\right)^{2}=\frac{g}{3}\)
\(\frac{R}{R+h}=\frac{1}{\sqrt{3}}\)
\(h =(\sqrt{3}-1) \,R\)
\(=(1.732-1) 6400\)
\(h =4685 \,km\)
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