Discusses the development of the Rutherford-Bohr atom. Indicates how the objectives of the historian may differ from those of the retrospecting or historicizing physicist. (Author/SK)

Describes a technique whereby qualitatively correct models of differentially rotating degenerate stars may be constructed by simple methods available to undergraduate students. (Author/JN)

Presents an elementary formulation of the work expenditure corresponding to walking, the most common physical exercise. The model described is included in a physics course for freshmen in physical education and physical therapy. (Author/JN)

Describes how many of the geometrical and physical properties of the binary elastic collision of two particles can be represented by an isoceles trapezoid in the velocity space. (BB)

A model of Brownian motion is discussed which includes viscosity effects. The model lends itself to Monte Carlo simulation and thus is suitable for an elementary physics laboratory experiment. (BB)