Question

For an object of 1kg mass to escape the gravitational force of the earth, the kinetic energy imparted to it from the surface of the earth is approximately _____

(a) 5600 J

(b) 10200 J

(c) 11200 J

(d) 12000 J

I got this question in final exam.

My question is taken from Kinetic Energy topic in section Work, Energy and Power of Physics – Class 11

Answer 1

Right option is (a) 5600 J

To explain I would say: Escape velocity of earth from the surface (v) = 11.2 km/s

 = 11,200 m/s

KE = (1/2) x m x v^2

 = (1/2) x 1 x 11,200

 = 5600 J.