Ok, this is a pretty hard problem I dont really know how to start. The set up is as follows, there is a block M and on the top edge of it there is a pulley, set up ontop of mass M is a mass m1, and thats connected to mass m2 that is on the right hand side of mass M. There is no friction and the cords are massless and everything. I really only need help setting up the free body diagrams for the three masses as I should be able to figure it out from there. I am confused also on why exactly mass M accelerates when there is no friction on mass m1 anyways. Any help would be great thanks.