[SOLVED] Gravitation Problem 1. The problem statement, all variables and given/known data The moon has a mass of 7.7times10^22kg and radius 1.7times10^6m. Calculate: a) The gravitational potential at its surface. b) The work needed to completely remove a 1.5times10^3kg space craft from its surface into outer space. c) What is the minimum speed which a body must have to escape from the moons gravitational field? 2. Relevant equations Vg=-GM/r Ep=GMm/r Ek=.5m(vsquared) Vg is the gravitational potential Ep is potential energy 3. The attempt at a solution a) Vg=GM/r G=6.67times10^-11 M=7.7times10^22kg r=1.7times10^6m Plug in the numbers and I get -3.0times10^6 b)Ep=Gmm/r M=7.7times10^22Kg m=1.5times10^3Kg r=1.7times10^6 Plug in numbers and get -4.5times10^9 Joules c)In need help on this one.