1. The problem statement, all variables and given/known data Newton's second law is given by F = dp/dt. If the force is always parallel to the velocity, show that F = gamma3ma 2. Relevant equations p = gamma*mv gamma = 1/(1-v2/c2)1/2 3. The attempt at a solution I really have no clue where to begin. This is what I've done so far, but I don't think I'm even on the right track. F = dp/dt = gamma3ma = [1/(1-v2/c2)1/2]3ma =1/(1-v2/c2)3/2ma =1/(1 - 3v2/c2 + 3v4/c4 - v6/c6)1/2ma Thats as far as i get on the right side. For the left, all i can manage is dp/dt = d/dx p = d/dx gamma*mv This is where I get confused. gamma and m are constant, so does dp/dt = gamma*m*dv/dt? Some clarification would be great. Thanks!