Hello: Here is a picture: _____ _______|____|____ _______|________________|_______ the top block has mass 10 kg, and the bottom slab has mass 40 kg. The bottom slab lies on a frictionless surface. Between the block and slab, the coefficient of static friction is 0.60 and the coefficient of kinetic friction is 0.40. The slab is pulled by a horizontal force F of magnitude of 100N to the left. What are the resulting acceleration of the block and the slab? Since we have 100N pulling the block, would the acceleration of the block be: 100 - 0.40*10*9.8 = 10*a? This 100 N is enough to move the block given the static friction. But I'm not sure about the slab? Would it be 100 = (40 + 10)*a? But that seems too simple... Many thanks.