Carrying out classroom experiments that demonstrate Boyle's law and Gay-Lussac's law can be challenging. Even if we are able to conduct classroom experiments using pressure gauges and syringes, the results of these experiments do little to illuminate the kinetic theory of gases. However, molecular dynamics simulations that run on computers allow…

An elementary formalism is developed for representing curved space-time which allows transparent qualitative explanation of general relativistic effects and is used to make a conceptual analysis of Einstein's principle of equivalence. A final section outlines a number of student activities. (Author/SK)

Regrouping cars from incoming trains into blocks of cars for outgoing trains is accomplished in railroad "hump" classification yards. Discusses: hardware and software elements of such installations; physical models on which software is based; success in predicting/regulating car speeds; and results of recent research into factors…