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Thread: Please Help !!!

  1. #1
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    Please Help !!!

    Could somebody Please work this problem out for me ?

    The thermal efficiency,e, of a heat engine is
    defined by e = (Qh-Qc)/Qh, where Qh is the heat absorbed in one cycle and Qc is the heat released into a reservoir in one cycle. Find (d^2e)/(dQh^2).
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by mayster17
    Could somebody Please work this problem out for me ?

    The thermal efficiency,e, of a heat engine is
    defined by e = (Qh-Qc)/Qh, where Qh is the heat absorbed in one cycle and Qc is the heat released into a reservoir in one cycle. Find (d^2e)/(dQh^2).
    $\displaystyle e=\frac{Q_h-Q_c}{Q_h}=1-\frac{Q_c}{Q_h}$

    Assuming that $\displaystyle Q_c$ is not a function of $\displaystyle Q_h$:

    $\displaystyle \frac{de}{dQ_h}=\frac{Q_c}{Q_h^2} $

    so:

    $\displaystyle \frac{d^2e}{dQ_h^2}=-2\frac{Q_c}{Q_h^3} $

    RonL
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