Two blocks are stacked on top of one another (7 kg and 12 kg). A 50 N force is applied to the bottom block. There is 8 N of friction between the bottom block and the desk. Show a free body diagram for the system and the individual blocks. The static friction between the two blocks is what keeps the top one from sliding off. Does it matter which block is on the top/bottom? Does the coefficient of static friction change?