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Homework Help: A diatomic ideal gas such as air. . .

  1. Feb 7, 2010 #1
    A diatomic ideal gas such as air, for which γ = 1.4, expands adiabatically to 40 times its original volume.
    (a) By what factor does the temperature change?
    (b) By what factor does the pressure change?

    I'm not sure how to attempt/approach this one. If anyone has any suggestions, it would be greatly appreciated.

    I tried using the equation T = T(not) - (mgh/R)*(gamma-1/gamma) but I didn't get anywhere, because I'm not sure where the expanding 40 times it's original volume comes in.
     
  2. jcsd
  3. Feb 7, 2010 #2

    cepheid

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    For adiabatic expansion, there is a simple relationship that involves the initial temperature and initial volume, final temperature and final volume, and gamma.
     
  4. Feb 7, 2010 #3
    Picture1.jpg

    Are you talking about this equation? I see it relates pressure, volume, and gamma, but not temperature.
     
  5. Feb 7, 2010 #4

    cepheid

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    Yeah, there's another one like that, only it relates a product involving T and V before and after the expansion. You could probably derive it from the relation you posted above + the ideal gas law, or you could look it up. It shouldn't be too hard to find.
     
  6. Feb 7, 2010 #5
    So I searched around and found this one. It relates 2 volumes and an initial temperature.

    Picture2.jpg
     
  7. Feb 7, 2010 #6

    cepheid

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