1. A 5kg block is held at rest against a vertical wall by a horizontal force of 100 newtons. 1-What is the frictional force exerted by the wall on the block 2-What is the minimum horizontal force needed to prevent the block from falling if the static coefficient of friction between the wall and the block is μs = .4 2. Relevant equations MAx = Right forces- Left Forces ( This is a homemade equation, basically the forces pushing from the wall are subtracted from the forces pushing against the wall. 3. The attempt at a solution I am unsure how to proceed with this problem. I know that for part 1, the frictional force should be about 49.1n, this comes from the equation shown above. If right forces- left forces= 0, then there is no movement, and therefore they must be equal. So 5kg*9.81m/s = 49.05N The second part is what confuses me, I fail to see a way to incorporate the friction coefficient into the problem in a meaningful way.