1. The problem statement, all variables and given/known data So the question revolves around two blocks, one of mass A and one of mass B. The Mass A block is on a smooth horizontal surface, connected by a thin chord that passes over a pulley to the second block, of Mass B. The question asks to draw a free body diagram of both objects, and then apply Newtons second law to find the formulas for the acceleration of the system, and for the tension of the chord. 2. Relevant equations block a: ƩF=Ft=ma block b: ƩF=Ft-mg=ma 3. The attempt at a solution I am able to draw the free body diagram, but when i try to find the formulas i get confused. I looked up the answer to the acceleration formula on the back of the book, and it is g(m(b))/m(a)+m(b). I worked backwards to find this, but i had to re-arrange my block b equation to ƩF=mg-Ft=ma, in order to get the acceleration. What i did was i substituted the block B (Ft) with the block A (ma), and then solved for acceleration. My first question regards the block B equation, i could not solve for the answer with my original equation (Ft-mg) , i had to flip them. How do i know which force comes first in the equation? Secondly, was my substitution between the two formulas correct? Thank you for your help!