1. The problem statement, all variables and given/known data Find a3. Assume that the system is placed on a frictionless table. Assumptions: 45 degree angles and rigid connectors between masses. 2. Relevant equations 3. The attempt at a solution So my first thought was just to sum all the forces on mass 1, find the reaction along 1-3 and use that to find a3, is that the correct approach? I.e. the reaction in beam 1-3 divided by the total mass of the system is the solution. Sum of the forces in x: mAx = F1 - R13 - R12 Sin45 mAy=R13cos45 were R12 is the reaction along beam 1-2 and R13 is the reaction along beam 1-3. But then I'm stuck, and I'm also not sure I'm approaching this correctly, perhaps I should use T=Iα somehow?