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Homework Help: Show that the work done in thermo

  1. Oct 23, 2005 #1
    hello the problem is as stated:
    a cylinder containing n moles of an ideal gas undergoes an adiabatic process. using [tex]W=-\int Pdv[/tex] and using the condition [tex]PV^\gamma=constant[/tex], show that the work done is:
    [tex]W=(\frac{1}{\gamma - 1}(PfVf - PiVi)[/tex] where Pf is final pressure, Pi is initial pressure...
    I tried substituting that [tex]P=\frac{constant}{V^\gamma}[/tex] into the integral, and evaluating from Vi to Vf, but this still leaves the gamma as an exponent. how can i go about solving this one?
    thanks
     
  2. jcsd
  3. Oct 23, 2005 #2

    Gokul43201

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    Right, you have an exponential term that looks like [itex]V^{1- \gamma} [/itex]. Write this as a product of two terms, one of which is V itself. What can you do with the other part ?
     
  4. Oct 24, 2005 #3
    awesome thanks for your help. all i needed was to see it as 1-gamma, instead of how i had it as -gamma +1. it made a lot of difference.
     
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