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Homework Help: 2 Parts of Thermodynamic Homework, help Please!

  1. Oct 5, 2005 #1
    Ok, the first question is this:

    It asks me to show that the following relation holds for a reversibe adiabatic expansion of an ideal gas:

    T/P ^(1 - (1/Gamma)) = constant​

    Where Gamma = the ratio of: C_p/C_v the specific heats with constant pressure and volume, respectively.

    I know that PV ^Gamma = constant and that TV ^(Gamma - 1) = constant.
    i just dont see the connection.

    Second question:

    An ideal gas undergoes an adiabatic reversible expansion from an initial state (T1, v1) to a final state (T2,v2).

    ln (T_2/T_1) = (Gamma - 1) ln (v_1/v_2)​
    again where Gamma = the ration of specific heats.

    Please help, thanks :eek:
  2. jcsd
  3. Oct 5, 2005 #2

    Andrew Mason

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    Homework Helper

    Express V in terms of P in the last equation:

    [tex]V = kP^{-\frac{1}{\gamma}}[/tex]

    This can be written:

    [tex]\frac{T_2}{T_1} = (\frac{V_1}{V_2})^{\gamma -1}[/tex]

    [tex]T_2V_2^{\gamma -1} = T_1V_1^{\gamma -1} [/tex]

  4. Oct 5, 2005 #3

    thank u, this is really helping me for the test i have on wed next week, appreciated. glad i found this site :biggrin:
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