{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture26

# Lecture26 - PHYSICS 220 Lecture 26 Thermodynamics I...

This preview shows pages 1–7. Sign up to view the full content.

Lecture 26 Purdue University, Physics 220 1 Lecture 26 Thermodynamics I Textbook Sections: 16.1-16.5 PHYSICS 220

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

View Full Document
Lecture 26 Purdue University, Physics 220 2 First Law of Thermodynamics Δ U = Q - W Heat flow into system Increase in internal energy of system Work done by system Equivalent ways of writing 1st Law: Q = Δ U + W The change in internal energy of a system ( Δ U) is equal to the heat flow into the system (Q) minus the work done by the system (W) Energy Conservation
Lecture 26 Purdue University, Physics 220 3 Signs You are heating some soup in a pan on the stove. To keep it from burning, you also stir the soup. Apply the 1 st law of thermodynamics to the soup. What is the sign of A) Q B) W C) Δ U Positive, heat flows into soup Negative, stirring does work on soup Positive, soup gets warmer

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

View Full Document
iClicker Lecture 26 Purdue University, Physics 220 4 A system is acted on by its surroundings in such a way that it receives 50 J of heat while simultaneously doing 20 J of work. What is its net change in internal energy? 1. 70 J 2. 30 J 3. zero 4. -30 J
Lecture 26 Purdue University, Physics 220 5 W = P Δ V W > 0 if Δ V > 0 expanding system does positive work W < 0 if Δ V < 0 contracting system does negative work W = 0 if Δ V = 0 system with constant volume does no work Work Done by a System M M Δ y W = F d cos θ = P A d = P A Δ y = P Δ V

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

View Full Document
Lecture 26
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}