http://www.ht-technology.com/temp/03-p01.jpg [Broken](adsbygoogle = window.adsbygoogle || []).push({});

I am trying to figure out this problem and could use a little bit of help. Escuse me if my LaTex is bad, this is my first time.

One mole of an ideal monatomic gas is caused to go through the cycle shown in the figure (all processes are reversible). Express all answers in terms of the pressure [tex] p_0 [/tex] and the volume [tex] V_0 [/tex] at a point [tex] a [/tex] in the diagram.

a) How much work is done on the gas in expanding the gas from a to c along the path abc?

We can work out this by summing the work from ab and bc. ab is an isobaric process, so W = [tex] P ( V_2 - V_1 ) [/tex] ---> [tex] P_0 ( 4 V_0 - V_0 ) [/tex] = [tex] 3 V_o p_o [/tex]

bc is an isochoric process, so no work is done. The final answer is as above.

That one wasn't so bad.

b) What is the change in internal energy and entropy in going from b to c?

This is isochoric process. [tex] \Delta U = m C_v \Delta T [/tex] and [tex] \Delta S = \int \frac {dQ} {T} [/tex]

My problem is that I don't really understand where to go from here. since [tex] C_v [/tex] is throwing me off a bit. How to solve these in terms of what is asked for? And with entropy, can I find a ratio of T in terms of pressure and volume? What do I really need to do here?

c) What is the change in internal energy and entropy in going through one complete cycle?

Since this is a cyclic reversible process that starts and ends at a, the change in internal energy and the entropy must both be 0. Do I need to say more? Should I prove this or is it just too obvious?

Thanks in advance for your help, and any comments are welcomed :-)

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Help with Thermodynamics

**Physics Forums | Science Articles, Homework Help, Discussion**