# Recent content by Metaleer

1. ### Heat exchanged between two gases

update: I spoke to a professor from the Thermodynamics department, and apparently, there's an error on the original exam sheet. During this particular examination, they made it known to the students then and there that where it said: "The wall is free to move back and forth and is not...
2. ### Heat exchanged between two gases

That would be nice of you. I think I have the book here somewhere (the 6th edition), so I'll try and look for it in the Entropy chapter. If I can't find it, I'll let you know. :biggrin:
3. ### Heat exchanged between two gases

I see, that's interesting. Did you actually happen to see how the components of the compressor moved, that is, if it's safe to assume that it moved in a quasistatic manner? Because if it did, then I may have my answer. :biggrin:
4. ### Heat exchanged between two gases

Are you sure the process can be considered polytropic? I mean, the expansion of one gas/compression of the other seems like an internal irreversibility to me, so during that process, the pressure isn't a well-defined property (you got turbulence and in general a fairly complicated gas dynamics...
5. ### Heat exchanged between two gases

Hm, and also, m*Cv*delta T happens to be the change of internal energy, so if I use that formula, it'd be like saying that neither gas does work, nor has work done on it. Is that true in this case?
6. ### Heat exchanged between two gases

But can I use C_v? I mean, the volume isn't constant for each gas, the non-adiabatic wall which separates both is free to move around.
7. ### Heat exchanged between two gases

Hello, LawrenceC! Thanks for replying. :smile: Nothing crosses the boundary if we take all of the system, and the total internal energy of the system remains constant; internal energy of an ideal gas is solely a function of temperature. As you can see, I've already used all this to obtain the...
8. ### Potential difference

You're welcome. :biggrin:
9. ### Is the Carnot efficiency valid for fuel cells?

Hey, thanks for answering. :smile: Well, your particular question is addressed in section 4 of the article. They state: The first thing they do to answer the question is to consider the high temperature reservoir: They then introduce a modified heat engine, where the high temperature...
10. ### Potential difference

The I in my explanation was the I of an arbitrary branch in which a shortcircuit is produced, I didn't use the same circuit as the one given. That's why I said V = IR, and not V = (I-i)R. The I of my example would be extrapolated to whatever it need be, per particular circuit.
11. ### Is the Carnot efficiency valid for fuel cells?

So, I've read in books and on Wikipedia (see for instance http://en.wikipedia.org/wiki/Carnot%27s_theorem_%28thermodynamics%29#Applicability_to_fuel_cells_and_batteries) that the Carnot efficiency cannot be applied to a fuel cell because it is not a heat engine that produces work, operating...
12. ### Potential difference

AB seems to be a shortcircuit. That is a potential difference of 0, so if you end up getting that, it's nothing to worry about. If you got something other than 0, that's when you should be worried. :wink: Basically, you can think of a shortcircuit as taking a branch with a single resistor R...
13. ### Heat exchanged between two gases

Homework Statement A horizontal container with adiabatic walls has a vertical wall inside it which divides the container in two. The wall is free to move back and forth and is not adiabatic. Initially, 1 kg of air is in the compartment to the left of the wall, at 5 bar and 350 K, and to the...
14. ### Incorrect solution to impulsive dynamics problem?

I am well aware that there is no such thing as a body with infinite rigidity. However, within the framework of Classical Mechanics, where perfectly rigid bodies are allowed, this loss of energy is what surprised me. :biggrin:
15. ### Incorrect solution to impulsive dynamics problem?

AlephZero, D H, thanks a lot for the interesting discussion and interesting points you have raised. However, one thing still bothers me. AlephZero, you have said that the kinetic energy changes in this problem because it is an inelastic collision. Usually, in an inelastic collision, changes...