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Homework Help: Heat on PV Graphs

  1. Dec 1, 2005 #1
    How do i calculate Q transferred in a PV graph (Pressure / Volume)? More specifcally, when it is a slope. All that was given is pressure and volume from the graph.

    Also, in an isochoric process, how would one go about finding Q? I spent so much time on thermodynamics yet i still dont know how to find it.
  2. jcsd
  3. Dec 1, 2005 #2


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    Homework Helper

    Generally, there is no direct way to do so. You have to consider that

    [tex]U = Q - W[/tex]

    The internal energy is dependant on temperature. Work is always a function of pressure and change in volume. There are interesting relationships for example if the process is adiabatic, so it depends on the situation. A combination of the ideal gas equation, adiabatic equation or use of saturation/compressed water/refrigerant tables may be needed depending on your problem.
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