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Homework Help: Thermodynamics - know process, work and change in entropy. Final temperature?

  1. Sep 14, 2008 #1
    So, the problem is:
    A 200-gram sample of dry air is heated isobarically. Its entropy increases by 19.2 J/K and the work done by expansion is 1.61x103 J. Solve for the final temperature of the air.

    Okay, since p=const => dq=CpdT thus instead of dq=du+dw we can write
    can find dq=460.46
    So i know dq,du,dw,d[tex]\phi[/tex], but how do I get final temperature? All I can find is dT but it's useless sine I don't know initial temperature.
    And where do I put mass and how to use the d[tex]\phi[/tex]=dq/T formula? Looks like it will be needed here...

    Thanks a lot in advance!
  2. jcsd
  3. Sep 14, 2008 #2
    nevermind. solved it.
  4. Sep 14, 2008 #3
    Aw. I have this problem too and I'm stuck on it. :(
  5. Sep 14, 2008 #4
    Get Tfinal - Tinitial through work, then you can solve integral dphi=dq/t and get the answer for Tfinal.
  6. Sep 16, 2008 #5
    I have this problem too and i still do not understand how you can solve for T final if there is not an initial temp given.
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