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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- Jun 13th 2006, 12:26 PM #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).

- Jun 13th 2006, 12:53 PM #2

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Originally Posted by**mayster17**

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