Gravitation Question 153

Question: Given mass of the moon is 1/81 of the mass of the earth and corresponding radius is 1/4 of the earth. If escape velocity on the earth surface is11.2 km/s, the value of same on the surface of the moon is [CPMT 1997; AIIMS 2000; Pb. PMT 2001]

Options:

A) 0.14 km/s

B) 0.5 km/s

C) 2.5 km/s

D) 5 km/s

Show Answer

Answer:

Correct Answer: C

Solution:

On earth $ [v _{e}=\sqrt{\frac{2GM}{R}}=11.2,,km/s] $

On moon $ [v _{m}=\sqrt{\frac{2GM\times 4}{81\times R}}=\frac{2}{9},\sqrt{\frac{2GM}{R}}] $ $ [=\frac{2}{9}\times 11.2=2.5,,km/s] $



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