A particle of mass $100~g$ is kept on the surface of a uniform sphere of mass $10~kg$ and radius $10

Question

A particle of mass $100~g$ is kept on the surface of a uniform sphere of mass $10~kg$ and radius $10~cm$. Find the work to be done against the gravitational force between them to take the particle far away from the sphere. (Use $G = 6.67 	imes 10^{-11}$)

Professor PC Thomas Classes · Answer

Work $W = \Delta U = 0 - (-\frac{GMm}{R}) = \frac{6.67 	imes 10^{-11} 	imes 10 	imes 0.1}{0.1} = 6.67 	imes 10^{-10}~J$.