One kilogram of the explosive TNT supplies an explosive energy of about 4.2×10^6 J. Let’s see what that energy can achieve in lifting objects from Earth’s surface to altitudes of hundreds of kilometers. We approach the issue through gravitational potential energy. Assume the acceleration due to gravity is constant at g = 9.81 m/s2 from Earth’s surface up to an altitude of 510 km above the surface. (A satellite at such an altitude would be in a “low Earth orbit.”) What is the gravitational potential energy, in joules, of a 1.0-kg object at that altitude, taking the reference level for gravitational potential energy (U = 0) at Earth’s surface.