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Homework Help: Thermodynamics [IdealGases,W,Q, etc.] Much Help Needed-Detailed questions in descrip.

  1. Jan 10, 2013 #1
    I'm sorry I cannot conform to the default format Physicsforums.com; it is because I do not even know the first step to solving these sorts of problems, I don't know which equations to use which is a major problem. Here are the types of questions I require understanding.
    An ideal gas goes through three processes (A>B>C>[A]) (Triangular form) (PV Chart)
    How would I figure out The Q, W, and ΔU (internal energy) for A to B, B to C, C to A?
    On another graph using variables but this time with numerical values for P and V on the axis, how would I find the work done by a monatomic ideal gas as it expands from point A to point C along the path shown in the figure? Also, how much heat would be absorbed BY the gas during this process?
    Finding the net work, heat, and ΔU in another PV Graph with data on the axis-es?
    Calculating temperature, work, and/or internal energy in another PV Graph?
    Whether or not W, Q, or ΔU is positive(gained) or negative(released) in an ideal gas system as well as how those three (Q,W,..U) are related?

    I really wish to work on the problems myself, so I have only asked what procedures I should take.
    Here is a list of equations I have scavenged.

    ΔU = Won + Q

    ΔU = (3/2)nRΔT

    Won = -PΔV

    P1V1 = P2V2

    (P1V1)/T2 = (P2V2)/T2

    PV = nRT

    Is there any important equation that I am missing?
    Last edited: Jan 10, 2013
  2. jcsd
  3. Jan 12, 2013 #2
    Re: Thermodynamics [IdealGases,W,Q, etc.] Much Help Needed-Detailed questions in desc

    I think that since you are working with idel gasses, you can dervie most of the stuff from 3-4 equations, namely:
    The ideal gas law : pV = nRT
    The Laws of thermodynamics.(2-3 laws is useful).

    If you want to find the Work done during a isothermal(T constant) step e.g.:
    [itex] W = -\int\limits_{V_1}^{V_2}\! p\,\text{d}V = -\int\limits_{V_1}^{V_2}\! \dfrac{nRT}{V}\,\text{d}V = -nRT\left(\ln(V_2)-\ln(V_1)\right) = -nRT\ln\left(\dfrac{V_2}{V_1}\right)[/itex]
    I hope that I understood your question.
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