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This screenshot is from the Carnot Cycle page on Wikipedia. In the "Stages" section, it says that:

The gas expansion is propelled by absorption of heat energy, $Q_1$, and of entropy, $\Delta S=Q_1/T_1$ from the high temperature reservoir.

Why do they mention the second part about the entropy? They speak of it as though it is a second, distinct cause of the gas's expansion. It seems redundant to mention the entropy because during this isothermal stage, heat is increasing, yes, but that's already mentioned by "propelled by absoption of heat energy". Is it accurate the way it's written or nah?

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  • $\begingroup$ Maybe there is intricacy in the language; but the fact is true; gas expansion causes the entropy to increase and not the vice-versa. But still, you can correlate the entropy increase with the expansion. That's it. And ultimately it all boils down to the calculation and it doesn't matter what language has been used till the equations are correct. $\endgroup$
    – user36790
    Feb 26, 2016 at 4:11
  • $\begingroup$ @user36790 that's what I was thinking too. It was just worded so strangely. $\endgroup$ Feb 26, 2016 at 15:17
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    $\begingroup$ yep! It's just word play and nothing. $\endgroup$
    – user36790
    Feb 26, 2016 at 15:23

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it's $dS = \frac{dQ}{T} $

It's the change/flow of heat in the system(s), not just the heat. This is where you confusion lies, as the Carnot Cycle is a perfect engine.

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