Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Thermodynamics problem

  1. Apr 20, 2005 #1
    Having trouble with a thermodynamics problem

    I'm having a bit of a problem with some of the homework in my thermodynamics class.
    Question (Water at 20 C, 100 kPa is compressed isothermally to 50 MPa. Determine the work required per unit mass. )
    using the tables I found:
    State 1
    [tex]T_1=20C[/tex]
    [tex]P_1=.100MPa[/tex]
    [tex]v_1=.001022[/tex] [tex]m^3/kg[/tex]
    State 2
    [tex]T_2=20C[/tex]
    [tex]P_2=50MPa[/tex]
    [tex]v_2=.0009804[/tex] [tex]m^3/kg[/tex]

    However, according to the tables, both states are compressed/subcooled . The only method I found to solve for work in an isothermal process applied to ideal gases. I was thinking I needed to approximate this, I tried to plot as many points in between the states and do a curve fit to find function [tex]P(v)[/tex]. Then integrate [tex]Work = \int_{v_1}^{v_2}P(v) dv}[/tex]. If I can do it that way, what kind of line do I use? (2nd order polynomial, 3rd order polynomial, etc...)

    Thanks for any help.
     
    Last edited: Apr 21, 2005
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted