Internal energy, thermodynamics

[Niles]

[SOLVED] Internal energy, thermodynamics

Homework Statement

I have the equation for the internal energy:

U = (f/2) * N * k * T, where f is the degrees of freedom, N is the number of molecules, k is Bolzmann's constant and T is the temperature in Kelvin.

This can be written as U = (f/2)*p*V using the ideal gas law. Differentiating this I get:

delta U = (f/2)*(delta_p*V + p*delta_V).

In this equation, I know what delta_p and delta_V are, but what about V and p? Are they the initial or final states?

Thanks in advance.

 

[kamerling]

V and P are just what they were before you differentiated the expression.

you get delta_U as a function of P, V, Delta_p and delta_U. V and p are NOT the initial or final values.

 

[Niles]

I'm sorry, but I don't understand what you mean.

V and p are not the final or initial values? If not, what are they then?

 

[Niles]

I realized I submitted this thread in the wrong category - I have made a new thread in the "Advanced Physics"-section:

https://www.physicsforums.com/showthread.php?t=215356