Hey, Ok here's the problem. A house has a roof with the dimensions in drawing. Determine the magnitude and direction of the net force that the atmosphere applies to the roof when the outside pressure rises suddenly by 10.0mm of mercury, before the pressure in the attic can adjust. Ok here's what I got so far... Ok so there are three forces in the vertical direction. One upwards on the roof and the the other two downwards, namely atmospheric pressure (P1) and weight (W). The other being the opposite force P2, acting upwards. So the Fnet is really just the sum of these forces right? So to find force for P1 and P2, I just used the Pressure x Area = force formula for both, except instead of atmospheric pressure, I added 10 to 760 and converted back into Pa. Then I got the forces and subtracted, and I also found the weight to be 2816N, I also subtract this number. I get something like 1.81 x 10^6 N in the downward direction. Something's wrong... Any ideas?