PHYS 1750: SELECTED TOPICS in PHYSICS
LECTURE 23. First and Second Law of Thermodynamics.

14.0.	Heat vs. Internal Energy
	1.	Forms of heat (all randomly distributed)
		a.	Translational KE in three directions
		b.	Molecular rotation (atoms cannot rotate!)
		c.	Molecular vibration
	2.	Other internal energies
		a.	Chemical bonds
		b.	Nuclear energy
		c.	Strain energy...
	3.	Heat transfer ONLY if there is a temperature difference
	4.	Thermal energy CAN increase without heat transfer (e.g. compression)
14.1.	The First Law (really conservation of E)
	1.	ΔU: a change in internal energy
	2.	Q: heat transfer INTO system
	3.	W: work done BY system
	4.	ΔU = Q - W does NOT depend on path
14.2.	Simple Processes
	1.	Q: heat transfer INTO system
		a.	Q = mcΔT
		b.	Depends on the "path" in P-V diagram
	2.	W: work done BY system
		a.	W = FΔx = PAΔx = PΔV
		b.	Depends on the "path" in P-V diagram
	3.	Note: for an ideal gas, U = 3NkT /2 = 3nRT /2 = 3PV /2
	4.	Adiabatic process: Q added = 0
14.3.	The Second Law
		Essentially: no process can convert heat to mechanical energy with 100% efficiency; energy will always be lost to the environment
14.6+.	Entropy and Disorder
	1.	Δ S = Δ Q/T
	2.	2nd Law: all processes increase S in isolated systems
	3.	S = k*ln(w)
		w = probability of distribution

Review Questions
Lecture 24: Simple Harmonic Motion