Air pressure problem

jeudi 3 avril 2014

The question asks; "Assuming that the density of air is a constant 1.3 kg/m3 and that the air pressure is 1 bar, what is the pressure at the top of a 500 meter high skyscraper?"



I'm having trouble setting something up but here is what I do have;

Regarding liquids we know that F = (Rho)(height)(g) so I want to say that whatever "causes" the "air to push down" on the ground at 1 bar of pressure should have 500 meters worth of "height" removed from it. So force pushing down = 1 bar and (force pushing down) - 500 meters = answer.

So (Difference in force) = (density)(g)(height difference) where given density is in Kg/m^3, height is in m and g is m/s^2. Summing up these values we get Kg/m*s^2 Which is equal to a Newton. The atmospheric pressure is Newtons/m^2.

If I ignore this discrepancy (because the pressure is measuring F/A, and I'm solving just for the force) and solve to problem I end up with a huge number 1.3*8.9*500 which is obviously incorrect. Can someone please steer me in the right direction? thanks





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