Hi guys. I haven't had physics in a couple of years and I'm trying to study for the MCATs. I've always had trouble with levers so I would really appreciate it if I could get some help. In particular, the following scenario confuses me: Say you have a man standing on a board, the fulcrum is to the left of the man's center of gravity, and he is pulling up on the right edge of the board. It is to my understanding that in such scenarios, the upward force applied by the man's arm is irrelevant towards calculations of net torque around the fulcrum because of the downward reactionary force applied by his feet, and that the net torque on the fulcrum is determined purely by the man's weight at his center of gravity. This makes sense to me intuitively, but when I try to work out the numbers, I confuse myself. Let's say the board's length is 10m, the fulcrum is located all the way at the left end, the man's center of mass is 1m from the left, and the man is pulling up on the rightmost edge of the board. I'm assuming that the reactionary force exerted by his feet on the board is equal and opposite to the upward force exerted by his arms, which we will call F. Taking counter-clockwise rotation to be positive, the net torque around the fulcrum can then be calculated as: torque = F(10) - F(1) - mg(1) = F(9) - mg(1) This equation is obviously wrong because it suggests that in such a scenario, the man is able to lift himself up off the floor. Essentially, to take filght. I know I made a mistake somewhere. Please help.