question_answer

Escape velocity from earth is 11.2 km/s. Another planet of same mass has radius 1/4 times that of earth. What is the escape velocity from another planet?                                          [AIPMT 2000]

A) 11.2 km/s

B) 44.8 km/s

C) 22.4 km/s

D) 5.6 km/s

Correct Answer: C

Solution :

Key Idea: The escape velocity from earth's surface is

Escape velocity is given by

From a planet,

Therefore,

It is given that, mass of planet = Mass of earth

i.e.,

So,                           (i)

Given

and

Substituting in Eq. (i) we have