1. The problem statement, all variables and given/known data two boards of length 5m and 8m are hinged together and the hinge supported 4m above the ground, thus forming a double inclined plane 13m long measured along the slopes. Two blocks of equal weight are placed on the boards and connected by a cord passing over a frictionless pulley at the apex. If the coefficent of friction between blocks and boards is 0.3 a) show that the system is in equilibrium. http://img525.imageshack.us/img525/3209/q10fs0.jpg diagram 2. Relevant equations 3. The attempt at a solution Block A: The left one. FN=mgcos53.13deg Frictionforce=mgcos53.15deg*(0.3) =0.18mg Force=mgsin53.13deg =0.8mg Block B: The right one. FN=mgcos30deg Frictionforce=mgcos30deg*(0.3) =0.2598mg Force=mgsin30deg =0.5mg If these calculations are correct then I dont see how they are in equilibrium.