1. The problem statement, all variables and given/known data [PLAIN]http://img834.imageshack.us/img834/6920/captureqt.jpg [Broken] 2. Relevant equations f=ma 3. The attempt at a solution Fsum=Fl + Fr=(m1+m2+m3)a 26+-8=(2+8+4)a a=18/14=1.28571 f=ma f=4(1.28571)=5.14268N I know this is incorrect. The force of 4kg block pushes on the 8kg the same as the 8kg pushes on the 4kg, but the way I calculated it doesn't work with that but I know of no other way.