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

2. Chapter 15 Temperature and Heat THERMODYNAMICS © 2003 J. F. Becker San Jose State University Physics 52 Heat and Optics

4. Fig. 15-1 Thermometers are used to measure temperature – a measure of hotness and coldness. (a) A system whose temperature is specified by the value of the length L. (b) A system whose temperature is specified by the value of the pressure p.

5. Fig. 15-2 The Zeroeth Law of Thermodynamics. (a) If systems A and B are each in thermal equilibrium with system C, then (b) A and B are in thermal equilibrium with each other. Blue = insulation, red = conducting material.

6. Fig. 15-3 (a) A bimetallic strip bends when heated because one metal (red) expands more than the other. (b) A bimetallic strip, usually in the form of a spiral, may be used as a thermometer.

7. Fig. 15-3 Graph of absolute pressure versus temperature for a constant-volume low- density gas thermometer.

8. Fig. 15-6 (a) We can visualize the forces between neighboring atoms by imagining them to be connected by springs that are easier to stretch than to compress. (b) Graph of potential energy versus distance between neighboring atoms shows that the forces are not symmetrical.

9. Fig. 15-7 The volume of one gram of water in the temperature range from 0 o C to 10 o C. By 100 o C the volume will have increased to 1.034 cm 3. If the coefficient of volume expansion were constant the curve would be straight.

10. Fig. 15-9 The same temperature change of the same system may be accomplished by: (a) doing work on it or (b) adding heat to it.

11. Fig. 15-10 specific heat capacity of water as a function of temperature. ‘The value of c varies by less than1% between 0 o C and 100 o C.

12. Fig. 15-12 Graph of temperature versus time for a specimen of water initially in the solid phase (ice). Heat is added to the specimen at a constant rate.

13. Fig. 15-13 Steady-state heat flow due to conduction in a uniform rod.

14. Fig. 15-15 conduction of heat. We can approximate heat flow through the walls of a picnic cooler by heat flow through a single flat slab of styrofoam.

15. Fig. 15-16 Heat flow along two metal bars, one of steel and one of copper, connected end-to-end.

16. Fig. 15-18 Water has higher specific heat than land.

17. Fig. 15-19 Convection in a thunder storm. Hot, moist air is less dense that cool, dry air and hence is lifted by buoyancy.

18. Fig. 15-21 (Exercise 15-62) A long rod, insulated to prevent heat loss along its sides, is in perfect thermal contact with boiling water at one end and an ice-water mixture at the other end. H = dQ/dt = kA ( T H - T C ) / L

19. Fig. 15-24 (Problem 15-109) Electric water heated to supply a continuous supply of hot water.

20. Fig. 15-25 (Problem 15-112)

21. Review