Ok, let me see if I can explain this well enough. There's a horizontal circular rod governing the motion of a collar having mass .75kg. The coefficient of kinetic friction is .3 and the collar is given an initial speed of 4 m/s starting at theta=0. I need to determine the arclength the collar travels before coming to a rest. This problem doesn't seem all that hard until I try to solve it, mainly because the magnitude of the frictional force depends on instantaneous velocity. Can anyone help me?