The work done to raise a mass m from the surface of the earth to a height h, which is equal to the radius of the earth, is :
Answer & explanation
Correct answer: option 4
Work done : W = Ufinal - Uinitial
Ufinal = -\(\frac{G M m}{2 R}\)
Uinitial = -\(\frac{G M m}{R}\)
W = \(\frac{G M m}{2 R}\) = \(\frac{m g R}{2}\) (∵ GM = gR2)