EXPLANATION
Firstly we need to understand what is gravitational potential energy .
It is defined as the amount of work done in bringing a body from infinity to a point of gravitational region /space is called as gravitational potential energy.
that is given by :
U = -G Mm/r
G = Universal gravitational constant
M = mass of the earth
m = mass of an object , r is distance between object and earth.
Work is done without acceleration because if the mass is accelerates , work gives the both kinetic energy and gravitational potential energy, not just U.
