A particle of mass m is subjected to a repulsive force k/r^5, where k is a constant. Initially it is at a very large distance from the force center O and has a velocity of magnitude such that, if it were directed along a path through the center of the force, the closest distance of approach would be a. Actually, it is projected, with the same velocity, along a path which would pass the force center at a distance b if it were not deflected. Find the minimum linear velocity (in terms of k,a,b,m) that the particle experiences as it follows its trajectory. I have no idea how to go about doing this. Any suggestions would be well appreciated.