1. The problem statement, all variables and given/known data The uniform 22-kg bar is supported on the horizontal surface at A by a small roller of negligible mass. If the coefficient of kinetic friction between end B and the vertical surface is 0.19, calculate the initial acceleration of end A as the bar is released from rest in the position shown. The acceleration is positive if to the left, negative if to the right. I have attached an image of the question 2. Relevant equations 3. The attempt at a solution I summed the forces in the x and y directions ƩFx = max = -NB ƩFy = may = NA - mg - F F = ukN ƩFy = may= NA - mg + ukNB So, I have 4 unknowns: ax, NB, NA and ay and two equations. How do I find the other two equations needed to solve this problem? I considered taking the moment about B, but this then adds in two more unknowns: α and aG. I suspect that I may need to use relative accelerations equations, but is there another way?