Timeline for Thermodynamic cycles, when is the work negative/positive?
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| Jun 25, 2013 at 23:11 | comment | added | joshphysics | @DepeHb Using the sign conventions I used in the response, one would have $\delta W = +PdV$. This can be used with ideal gases for example. And yea, for isothermal processes you would use that expression along with the ideal gas law to write $P$ as a function of $V$, and then you would explicitly perform the integral. | |
| Jun 25, 2013 at 21:02 | comment | added | Spine Feast | Thanks for the answer. BTW, when is it true that $\delta W=-pdV$? I recall this being a useful tool for quick calculations, but surely its applicability is limited? For example, in path (3), the definition $\Delta T = 0$ implies $\Delta E =0$, so $\delta Q = \delta W$. But I know of no way to integrate $\delta Q$, and since it's not a state variable, I can't just write $Q_b - Q_a$... | |
| Jun 25, 2013 at 20:49 | vote | accept | Spine Feast | ||
| Jun 25, 2013 at 20:33 | history | answered | joshphysics | CC BY-SA 3.0 |