1. The problem statement, all variables and given/known data (see attachment) 2. Relevant equations 3. The attempt at a solution I am not sure how to begin with this one. I understand how the motion takes place but I am really not sure how to begin making the equations. Considering the first case, B moves down and since the string is inextensible, A moves to left. So the forces acting on B are its weight and the tension from the string. Right? But what are the forces acting on A except its weight and the normal reaction from ground? I can only see that the force arise from the pulley attached but how would I calculate that force? Any help is appreciated. Thanks!