1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Derive Gibbs function for dry air .

  1. Sep 22, 2011 #1
    1. The problem statement, all variables and given/known data

    1. Derive the Gibbs function g(T,P) for dry air. T = temp, P = pressure
    2. Derive the speed of sound (c) from the Gibbs function. Plot c as a function of temp and pressure.

    2. Relevant equations

    c = gp*squareroot(gTT/(g^2TP - gTT*gpp)

    I wasn't sure how to type it in but gp,gTT, etc. are partial derivatives with repect to p,TT, etc.

    g = I - T*entropy +P*specific volume



    3. The attempt at a solution

    I am having trouble getting g in terms of just P and T. I kind of did it, but I'm not sure exactly where I should end up.

    Also I am not getting anything for c that makes sense.
     
  2. jcsd
  3. Sep 22, 2011 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    If someone gave me T and P I would go to a table of entropies and enthalpies for dry air and compute g(T,p) = h(T,p) - Ts(T,p). Nice that h and s are state functions!

    There are several formulas to derive entropies and enthalpies if you assume an ideal gas.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Derive Gibbs function for dry air .
  1. Functional derivative (Replies: 4)

Loading...