(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A reversible heat engine operates between two reservoirs having temperatures T1 and T2 (T2 > T1). The temperature T1 of the cold reservoir remains constant, whereas the warmer reservoir consists of n moles of a gas at constant volume with specific heat capacity Cv. After the heat engine has operated for period of time [tex]\Delta[/tex]t, the temperature T2 has dropped to T1.

i) How much heat is extracted from the warmer reservoir during [tex]\Delta[/tex]t?

ii) What is the change of entropy of the warmer reservoir during [tex]\Delta[/tex]t?

iii) How much work did the engine produce during [tex]\Delta[/tex]t?

iv) What is the change in entropy of the universe during [tex]\Delta[/tex]t?

2. Relevant equations

Q = nCv[tex]\Delta[/tex]T

3. The attempt at a solution

i) Right for the first part im assuming [tex]\Delta[/tex]T corresponds to (T2 - T1), so the heat extracted is

Q = nCv(T2 - T1) ?

ii) For the next bit im not sure. It says the heat engine is reversable, which makes me think there's no change in entropy, however it hasnt completed a cycle in [tex]\Delta[/tex]t. So that cant be right... can it?

iii) For the work done W = Qh - Qc

and Qh (if my attempt at part one is right) is = nCv[tex]\Delta[/tex]T

so W = (nCv[tex]\Delta[/tex]T) - Qc ?

iv) And the last part is kind of the same problem I have with part two.

So for the bits ive done am I right, and for the entropy parts is it zero or not?

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# Homework Help: Heat engine problem

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