25. The variation of gravitational acceleration g with altitude y is given by:

where km is the radius of the Earth, and m/s2 is the gravitational acceleration at sea level. The change in the gravitational poten-

tial energy, U, of an object that is raised from the Earth is given by:
Determine the change in the potential energy of a satellite with a mass of 500 kg that is raised from the surface of the Earth to a height of 800 km.