1. The problem statement, all variables and given/known data -- This is out of Rendezvous With Rama by Arthur C. Clarke You know it is 907184 kg and is going 50,000 m/s So how much energy does it have right before it hits the earth? 2. Relevant equations Do I use Fg= Gm1m2/r^2 ? Ek=1/2mv^2? I have ΔE=1/2mv^2 written down as an equation to use as well. 3. The attempt at a solution I think I'm supposed to calculate the potential energy at 2 different spots and find the ΔE, but I'm not sure. E=Gm1m2/r+1/2mv^2 would that work?