I finally managed to work through my difficulty with frictionless force problems involving Newton's second law, but now what's throwing me off is how to throw friction into the mix. For this problem, for example: A 68 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 24° above the horizontal. (a) If the coefficient of static friction is 0.47, what minimum force magnitude is required from the rope to start the crate moving? (b) If the coefficient of kinetic friction = 0.29, what is the magnitude of the initial acceleration (m/s^2) of the crate? I know that I first need to draw a freebody diagram, and when I do, I can perceive 4 forces acting on the crate: Normal Force, Tension, Weight, and of course Friction. However, my problem is where to go from there.