Earth's radius = R miles, Mass of earth = M kg, mass body = m kg
Energy of the body at height 500mi = 800 km when projected:
Suppose it goes away from Earth and revolves in an Orbit around the Earth at radius X > R, then
Energy of the body at height X :
Let us say the body has very near zero velocity as it nears infinite distance away from Earth. If the body nears infinite distance, then its energy will be zero as R+X ⇒ Infinity.
So, Energy of the body at height 500mi to go to infinity