1. The problem statement, all variables and given/known data The hanging mass in the system is pulled down until the friction force is maximized between the other mass and the incline. Find the initial acceleration of the mass on the incline if the string is then cut. Let the average coefficient of kinetic friction be 80% the coefficient of static friction. 2. Relevant equations ##F=ma## and ##f=\mu N## 3. The attempt at a solution So the problem states that the hanging mass is pulled until the friction force (static since it's at rest) is maximized. I drew free body diagrams for both masses here http://i.imgur.com/vHQ4vJy.jpg. I understand that the problem is asking me to find the maximum static friction of the block on the incline (before it starts to move) but I don't know how to express that in an equation. Could someone explain how I would do this? *edit sorry for the big image, I'm not sure how to resize it.