Solve Difficult ThermalDynamics Questions

  • Thread starter Thread starter Lil Frank
  • Start date Start date
Lil Frank
Messages
2
Reaction score
0
Following questions are from my final. I found them pretty difficult. I hope someone help me with them. Thank you.

1 Please give a clear argument by using the concept of entropy to explain that the heat will always flow from the high temperature to the low temperature objects if there is no external work.

2 Please construct the plots of P versus V, T versus S, and S versus E_internal (a) for the isothermal expansion and isobaric expansion thermodynamic process.
(b) for the adiabatic expansion thermodynamic process.(Please point out the initial and final state on your curve.)

3 For adiabatic processes in an ideal gas, show that
(a)the bulk modulus is given by
dp
B = -V ——— =γP
dV And therefore
(b)the speed of the sound in the gas is v=√γp/ρ =√γRT/M

4 (This one is the most difficult one, can anyone help me with it?)
(a)Derive the entropy chang: ΔS=Sf-Si=nRln(Vf/Vi)+nCvln(Tf/Ti) for all reversible processes that take the ideal gas from state i to state f.
(b) Please use this relation to calculate the change in the entropy for a free expansion process from V to 4V. Please also give the reason that you may do in this way.
(c)Derive this increase of entropy with statistical mechanics(using the Boltsmann's entropy S=klnW,where k is the Boltsmann's constant,W the multiplicity of the confriguration).Before doing this,please give explain.
(Hint:lnN!=N(lnN)-N,while N is large)
 
Physics news on Phys.org
Here we don't help if you don't provide us with attempt to solutions and some relations/forumulas that you know.
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top