Ok, our teacher is pretty much insane and doesn't teach anything at all. I'm sure this problem is incredibly simple, but I'm just not sure how to do it. Original Problem: A 15.0 kg box is released on a 32 degree incline and accelerates down the incline at .30m/s/s. Find the friction force impeding its motion. What is the coefficient of kinetic friction? What I Did: I found Normal Force to be 127 N with Wcos(theta) but I don't know where to go from there. Any help would be much appreciated.