1. The problem statement, all variables and given/known data The coefficients of friction are Us = .4 and Uk = .3 between all surfaces of contact. Determine the force P for which motion of the 30kg block is impendinging if cable AB is attatched as shown 3. The attempt at a solution wups i forgot to lable AB but theres only 1 cable so the picture is clear im having trouble setting this one up. i dont know whether to start on the bottom block or the top. and im not sure if im setting up my forces correctly. heres what i have for the top block: sum Fy = N - (20)(9.8) = 0 ---> N = 196N sum Fx = Tab - Us(N) = 0 ---> Tab = Us(N) = .4(196) = 78.4N is that much correct? if it is then im not sure if im setting up the next part right. for the bottom block i have: sum Fy = N - (20)(9.8) - (30)(9.8) = 0 ----> N = 490N sum Fx = -P + Tab + (Us)(N) = 0 ---> P = 78.4 + (.4)(490) = 274.4N if i screwed up anything, its probably the horizontal forces. is Tab right or should it be (tab)(Us) ?