JEE Mains · Physics · STD 11 - 7. gravitation
An object of mass \(1 kg\) is taken to a height from the surface of earth which is equal to three times the radius of earth. The gain in potential energy of the object will be \(....MJ\)[If, \(g =10\,ms ^{-2}\) and radius of earth \(=6400\,km\) ]
- A \(48\)
- B \(24\)
- C \(36\)
- D \(12\)
Answer & Solution
Correct Answer
(A) \(48\)
Step-by-step Solution
Detailed explanation
\(U _{ i }=\frac{- GMm }{ R }\) \(U _{ f }=-\frac{ GMm }{4 R }\) \(\Delta U = U _{ f }- U _{ i }=\frac{3 GMm }{4 R }\) \(=\frac{3}{4} mgR\) \(=\frac{3}{4} \times 1 \times 10 \times 64 \times 10^{5}\) \(=48\,MJ\)
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