Question

If the kinetic energy of a satellite is halved, its orbital radius becomes _____

(a) 1/2 times

(b) 2 times

(c) 4 times

(d) infinity

This question was addressed to me during an interview for a job.

My query is from Gravitation in section Gravitation of Physics – Class 11

Answer 1

Correct choice is (b) 2 times

To explain I would say: The kinetic energy of a satellite is;

KE = (1/2) x (G x m x M)/r

r: Orbital radius

Let new kinetic energy be KE’

KE’ = KE/2

 = [(1/2) x (G x m x M)/r]/2

 = (1/2) x (G x m x M)/(2r)

 = (1/2) x (G x m x M)/r’

r’: New orbital radius

r’ = 2r.