1. The problem statement, all variables and given/known data A 12 N horizontal force F pushes a block weighing 5.0 N against a vertical wall. The coefficient of static friction between the wall and the block is 0.60, and the coefficient of kinetic friction is 0.40. Assume that the block is not moving initially. (a) will the block move? (b) in unit-vector notation, what is the force on the block from the wall? 2. Relevant equations f = (mu) * N 3. The attempt at a solution For (a), I just calculated fk, max and since it is greater than the weight of the block, the block will not move. I'm confused about part (b). The answer at the back of the book is (-12i + 5j) newtons. I understand the 12i part. That's just the normal force of the wall on the block. But where does the 5j come from? I thought the 5 newtons upwards were due to the friction and not the wall exerting a force on the block?