1. Physics 52 - Heat and Optics Dr. Joseph F. Becker Physics Department San Jose State University © 2003 J. F. Becker

2. Chapter 20 The Second Law of Thermodynamics

3. Schematic energy-flow diagram for a heat engine.

4. Cycle of a four-stroke internal- combustion engine: intake, compression, power, exhaust.

5. The pV diagram for the Otto cycle, an idealized model of the thermodynamic processes in a gasoline engine.

6. The pV diagram for the idealized Diesel cycle.

7. Schematic energy-flow diagram for a refrigerator.

8. Principle of a mechanical refrigeration cycle.

9. AC works on same principle as a refrigerator

10. Energy-flow diagrams for equivalent forms of the Second Law of Thermodynamics.

11. The Carnot cycle for an ideal gas. Isotherms in light-blue. Adiabats in dark-blue.

12. Second Law forbids this system.

13. Water molecules are arranged in a regular ordered way in an ice crystal.

14. Free expansion of an insulated ideal gas. In (c) the free-expansion process does not pass through equilibrium states from a to b. However, the entropy change S b – S a can be calculated by using the isothermal path shown or any reversible path from a to b.

15. (a) A reversible cyclic process for an ideal gas, shown as a red closed path. (b) The path can be approximated by a series of long thin Carnot cycles. The entropy change is zero for each Carnot cycle and for the actual cyclic process. (c) The entropy change S b – S a is the same for all paths connecting points a and b.

16. All possible microscopic states for 4 coins. There can be several microscopic states for each macroscopic state.

17. In a free expansion of N molecules in which the volume doubles, the number of possible microscopic states increases by 2 N

18. A passive solar collecting panel for home water heating.

19. A heat engine takes 0.350 mol of a diatomic ideal gas around the cycle.

21. Thermodynamic Processes for a Refrigerator.

23. A Stirling-cycle engine.

24. Fuel Economy and Automobile Performance.

25. Review