Ok here is another problem that I am stuck on! A 20.0kg sled is being pulled across a horizontal surface at a constant velocity. The pulling force has a magnitude of 80.0N and is directed at an angle 30.0 degrees above the horizontal. Determine the coefficient of friction. I think that Fn=(20.0)(9.80)(cos 30) and I know that uk=Fk/Fn and a=0m/s(sqr) but I am stuck on how to go about finding Fk? Am I on the right track?