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Silly question about air pressure

  1. Aug 17, 2011 #1
    1. The problem statement, all variables and given/known data

    I was reading that if you have a room with a floor of say 20 square meters, then the downward air pressure would be equal to almost 240 tons which is obviously more than enough to collapse the floor, but since there is an equal upward pressure coming from the air underneath the floor the pressures all cancel out and everything is fine.

    But pressure also varies according to temperature. So I was wondering, if you could isolate the two air masses, would it then be possible to change the pressure of the gas on each side of the floor such that there would be a great enough difference to cause the floor to collapse?
     
  2. jcsd
  3. Aug 17, 2011 #2

    Andrew Mason

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    Certainly. You would have to build very strong airtight rooms. If you were going to heat the upper chamber, the walls and ceilings would have to be stronger than the floor. Otherwise the walls and ceiling would explode before the floor collapsed. If you were going to cool the lower chamber to reduce its pressure, the walls below would have to withstand greater pressure than the floor.

    AM
     
  4. Aug 17, 2011 #3

    PhanthomJay

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    Temperature differentials do not cause significant changes in pressure unless they are extreme. But consider a commercial aircraft flying at 35,000 where air pressure outside may be about 3 psi (forgive the USA units), and inside the cabin is pressurized to say 12 psi. If the fuselage and windows were not strong enough to withstand the 9 psi pressure differential, the plane would be torn apart. Or if you could open a window, everything would be suctioned out of the plane, like you see in the movies, perhaps.
     
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