1. The problem statement, all variables and given/known data The upward normal force exerted by the floor is 620N on an elevator passenger who weighs 650N. 2. Relevant equations F=ma 3. The attempt at a solution I am reviewing all the Homework assigned so, I do got the answers. :) Anyways, the way I set this problem up was F=ma. First we need to know the mass, which we get by w=mg. 650 = m9.8 m = 66.33 now we plug into F=ma. Fnet = 66.33a I managed to get the acceleration of .455 , but my question here is , why is the net force 620-650 and not 650-620. Do we always subtract from the smaller force first? My first instinct was since gravity was larger it would be 650-620. What if it was this instead: "The upward normal force exerted by the floor is 700N on an elevator passenger who weighs 100N."? Would it be normal force-w or will it still be w-n. ? I just need a clarification.