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Homework Help: Heat capacity in ideal engine

  1. Dec 10, 2011 #1
    1. The problem statement, all variables and given/known data
    The question is presented as picture.

    2. Relevant equations
    What is the expression of this 'heat capacity C'?
    The x-process is isothermal then C=nCΔT=0?
    Please give me some ideas.

    3. The attempt at a solution
    set V1=V2, V3=V4, T1=T4, T2=T3, p1+p0=p2, p3-p0=p4
    constant volume process:ΔU=n*Cv*(T2-T1)=Cv*V1*p0/R where p0=p2-p1
    isothermal process:W=nRT1*ln(V3/V2)=nRT1*ln(p2/p3)
    Then I can't go any further.

    Attached Files:

  2. jcsd
  3. Dec 10, 2011 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    Heat capacity is defined as: C = ΔQ/ΔT. Since work is being done but there is no change in internal energy, ΔQ > 0. However, since it is isothermal, ΔT = 0. So what is the heat capacity, ΔQ/ΔT at all pressures (points) on the isothermal curve?

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