Advanced General Physics 323/324

Thermal Physics Unit T4 Kinetic Theory

Prerequisites: T1 and T2

Overview: This unit turns to the microscopic picture of matter as containing large numbers of atoms and/or molecules moving with a distribution of speeds determined by the temperature. The ideal gas equation of state can be understood in this picture, along with many other properties such as viscosity, heat conductivity, and diffusion of gases.


F. W. Sears and G. L. Salinger, Thermodynamics, Kinetic Theory, and Statistical Thermodynamics (S&S) Chapt. 9 - Kinetic Theory; Chapt. 10 - Intermolecular Forces and Transport Phenomena

Comment: One of the more difficult concepts in this unit is that of molecular flux, covered at the beginning of Chapt. 9. Make sure you understand this idea, and how molecules move with a range of speeds in all possible directions, and how many averages needed to evaluate certain quantities involve integrals over the three dimensional space of velocities.

After completing this unit you should understand:

  1. Molecular flux.
  2. Derivation of the ideal gas equation of state PV = nRT from kinetic theory arguments.
  3. Pressure from the kinetic theory point of view.
  4. Mean free path.
  5. Viscosity.


Chapt. 9: Problems 1,5,6,13,16,23; Chapt. 10, Problems 6,10,14,15;

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