Question

a body of mass m is raised from the earths surface to an altitude equal to the radius(R) of the earth. if g is the gravitational acceleration on earths surface the change in the potential energy of the body is,_______

Answer 1

gravitational potential energy of a body of mass 'm' on the surface of the earth radius 'R' and mass 'M' will be

U = -GMm/R

and at a height equal to earth's radius

U' = -GMm/(R+R) = -GMm/(2R)

so, change in potential energy will be

dU = U - U'

or

dU = -GMm/R - [-GMm/(2R)]

= (-GMm/R)[1 - 1/2]

thus, we get

dU = -GMm/2R