1. The problem statement, all variables and given/known data So there are two planets A and B whose centres are 6r apart. A and B has the same mass M and radius R. What is the minimum velocity(from the surface of B) of the rocket required to launch it from B so that it reaches A ? 2. Relevant equations F=GmM/R^2 3. The attempt at a solution So what i thought was at the mid point between the planets the rocket must have zero velocity so acceleration=GM/x^2 -GM/(6r-x)^2 and as a=v dv/dx then i integrated both sides with limits of 0&Vm(launch speed) for dv and 3R&5R for dx Is this right ?