1. The problem statement, all variables and given/known data Given: The universal gravitational constant G = 6.67 E-11, the mass of the earth M = 5.98E24, and its radius R = 6.7 E6. How much work must an external force do on the satellite to move it from a circular orbit of radius 2R to 3R, if its mass is 2000kg? Answer in Joules. 2. Relevant equations I know that E = -GMm/2r, where M is the mass of the earth and m = satellite. 3. The attempt at a solution So I calculated the total energy in each radii, for 2R, -GMm/4R for 3R, -GMm/6R then I subtract one from the other to get the net energy change. I don't know what to do after that. Please help. Thank you!