1. The problem statement, all variables and given/known data coefficient of kinetic friction = 0.15 Find the acceleration of block a. 2. Relevant equations see below 3. The attempt at a solution http://www.wolframalpha.com/input/?i=-200sin30%2B0.15*200cos30%2B2x%3D-200%2F32.2*a%3Bx-40%3D40%2F32.2*b%3Ba%3D0.5*b I used x for tension and a and b for the acceleration of the blocks. I assumed that the acceleration of block a is down the plane and so block b would go up, but the answer I got was negative! I tried assuming that block a goes up and block b goes down, but I got a negative answer again! Are the equations that I used wrong? or the blocks don't move at all?