Escape velocity of a body of 1 kg mass on a planet is 100m/s. Gravitational potential energy of the body at the planet is:
Escape velocity is given by formula
ve=√2GMR
Now gravitational potential energy
UG=−GMmR
UG=−12mve2
UG=−1×10022
UG=−5000J
Thus gravitational potential energy of the planet is −5kJ.