1. Physics and Astronomy THERMAL PHYSICS THERMAL PHYSICS U. MOHIDEEN

2. OUTLINE Concept of Temperature -How to Measure T? (Kelvin Scale) - What is Temperature? (Kinetic Theory of Gases) Concept of Heat & Heat Energy First Law of Thermodynamics & Energy Conservation Understanding of Work Done Teaching Awards 1 Distinguished Teacher of the Year 1 Distinguished Teaching Innovation Award Junior Faculty Research Awards 5 US National Science Foundation Career Award Winners 3 US Department of Energy Young Investigator Award Winners 2 US Office of Naval Research Young Investigator Award Winners 1 Sloan Foundation Fellow Senior Faculty Research Awards 7 American Physical Society Fellows 3 American Association Advancement Science Fellows 1 Guggenheim, 1 Humboldt 1 Bardeen Prize 1 Am. Physics Soc. Panofsky Prize

3. Zeroth Law (Idea of Temperature) 1.Idea of Thermal Equilibrium- Two bodies in contact have no thermal change between them 2.Temperature- Measure of Warmth (use thermometer or hands etc as something to measure) 3.Zeroth Law: Defines the idea of Temperature. If Object A in equilibrium with C (thermometer) and Object B in equilibrium with C, then A and B at same temperature as C.

4. How to Measure Temperature 1.Scales (Renkin, Faranheit, Kelvin) 2.Meaning of Absolute Scale

5. Meaning of Temperature 1.Kinetic Energy of Atoms & Molecules a. Kelvin Scale (constant volume Thermometer) PV=N k B T b. Maxwell’s Kinetic Theory (½ m 2 = ½ k B T) v rms = √3k B T/m N 2 molecule velocity at room temperature=510m/s 1140 mph !

6. Thermal Energy or Heat Energy Joules Experiments Proving Heat Energy is Kinetic Energy of Atoms & Molecules - Total Kinetic Energy of gas  Internal Energy Heat Energy Q proportional to # of atoms proportional change in T proportional degrees of freedom Latent Heat= Bond Energy

7. First Law of Thermodynamics Energy Conservation  U = Q - W Total Kinetic Energy of gas  Internal Energy (U) Q= Heat Energy change- Heat Gain is Positive Heat Lost is Negative from T change W= Work done by gas (Expands is positive & Compressed is negative) Explain Work done ON and Work done BY

8. Work Done Gas Processes: Iso thermal (Constant T) Iso baric (Constant P) Iso volumetric (Constat V) Adiabatic (No change in Q i.e. Q=0) Area under curve if P along y axis and V along x axis

9. Second Law of Thermodynamics

12. Statistical Definition of Entropy Entropy increase  Disorder Increase (Eg. Melting, Rotting etc)  To decrease entropy and create order, need to do work i.e. Not spontaneaous Process. Eg. Crystallization by cooling, Body functions with eating

13. Heat Engine Hot Reservoir (Steam Tank) Cold Reservoir (Outside Air) Engine Work Q hot Q cold thru exhaust http://www.animatedengines.com/otto.shtml

14. All Real Process No perpetual motion machines Energy wasted in every process Net Entropy increase as Spontaneous Change will happen (waste) Food Chain -  Fewer Predators Effeciency < 1

15. Thank You