1. The problem statement, all variables and given/known data If the force needed to start the motion of an object having a mass of 2.5 kg is 4.90 N, what is the coefficient of static friction? 2. Relevant equations f = uN Since u is missing, the formula is u = f/N 3. The attempt at a solution u = 4.90 N/(2.5 kg X 9.8 m/s2) u = 4.90 N/24.5 N u = 0.2 The problem is asking for the coefficient of static friction. I'm not sure if I got the answer for kinetic friction? I know the difference between the two but I don't know why the problem required static friction when it is talking about a moving object.