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Fundamental thermo systems problem

  1. Jan 31, 2014 #1
    1. Unit mass of a fluid at a pressure of 3 bar, and with a specific volume of 0.18 m3/kg, contained in a cylinder behind a piston expands reversibly to a pressure of 0.6 bar according to the law p = c/v2, where c is a constant. Calculate the work done during the process.



    2. P1V1=P2V2



    3. I know that the answer is 29.82 J/kg out of the system, but how to get it?
     
  2. jcsd
  3. Jan 31, 2014 #2
    c=p1*v12 but work=∫p*dv=∫c/v2*dv=c∫dv/v2 the rest is basic calculus. The answer units should be kj/kg
     
  4. Jan 31, 2014 #3
    c=Subscript[p, 1]*Subsuperscript[v, 1, 2] but work = \[Integral]p \[DifferentialD]v =\[Integral]c/v^2 \[DifferentialD]v = c \[Integral]1/v^2 \[DifferentialD]v the rest is basic calc. I believe the answer units is KJ/Kg
     
  5. Jan 31, 2014 #4
    Guess I can't copy mathematica text into the message box
     
  6. Jan 31, 2014 #5
    Thank you! I'll go through this tomorrow. I've been working on these problems the whole day. It is time for me to take a break. I appreciate the reply.
     
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