1. The problem statement, all variables and given/known data http://i.imgur.com/rjxR2.jpg 2. Relevant equations F = ma 3. The attempt at a solution I know that the rope is pulling the man up twice as much because there are two points of contact between him and the rope. I'm really just looking for somebody to explain why that is? It seems to me that when he pulls down on the rope, the chair will move with a force upwards, but the other side will move with a force downwards and he will basically be in the same position unless he lets go of the rope with his hands. What I'm trying to say is, the tension on each side of the rope is going in opposite directions. Why would it count as if the man is being pulled up twice when, the way I see it, the two forces should cancel each other out?