{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 37

# Lecture 37 - Lecture 37 pls-37.1 Entropy and the 2nd Law of...

This preview shows pages 1–3. Sign up to view the full content.

Lecture 37 pls-37.1 Entropy and the 2 nd Law of Thermodynamics Media: 1. Fan w/ hot, cold water and LN 2 2. Figs. 1, 2 1. S and S The entropy S is a function of the thermodynamic state of the system, similar to the internal energy U and pressure P . E.g., for an IMG, if we know N , V , and T , we know T Nk U B 2 3 = and T k V N P B = Similarly, = C N V N U Nk S B 2 3 ln For a system at temperature T , if we add a small amount of heat Q , then the change in entropy of the system is T Q S = Remember, Q is not a state function, but the entropy S is. Relationship to PV diagram ( Fig. 1 ): (i) On an adiabat 0 = Q Æ 0 = S Æ S is constant along an adiabat. That is, an adiabat is a constant entropy curve. ( C is a constant that depends upon the mass of the atoms in the gas)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Lecture 37 pls-37.2 (ii) Because S is a state function, there is a unique value of S (for the gas) at each point of the diagram (as is true for other state functions P , V , U , and T .) 2. Entropy and the Carnot Cycle —Carnot cycle = isotherm-adiabat cycle Fig. 2 : paths 1, 3: isotherms paths 2, 4: adiabats (i) Around the cycle A Æ B Æ
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 5

Lecture 37 - Lecture 37 pls-37.1 Entropy and the 2nd Law of...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online