An algebraic definition of time differentiation is presented and used to relate independent measurements of position and velocity. With this, students can grasp certain essential physical, geometric, and algebraic properties of motion and differentiation before undertaking the study of limits. (Author)

Describes a laboratory activity about measurement and its reliability for general education students. The measurement focuses on automobile speeds and allows for estimates of errors, experimental design, and relativity in addition to kinematical concepts. (DS)

Demonstrates erroneous results obtained if change in a vector under parallel transport about a closed path in Riemannian spacetime is made in a complete circuit rather than just half a circuit. (Author/SL)

Describes a lecture demonstration that has been effective in teaching the concept of the lack of simultaneity in introductory physics courses. The demonstration experiment can be used for studying the relationship between simultaneity and causality and as a conceptual device for analyzing the lack of simultaneity in special relativity thought…

Describes two simple, economic timers suitable for measuring time intervals with fractional millisecond resolution in physics experiments. (MLH)

Reviews the Hafele-Keating experiment on relativistic changes in eastward and westward moving cesium atomic clocks. Recommends the use of the Sagnac effect to remove the east-west time asymmetry and of the general-relativistic effect to elucidate the clock-rate changes. (CC)

By using the method of moments, it is shown that several important and apparently unrelated theorems describing average properties of stochastic systems are in fact particular cases of a general law; this method is applied to generalize the virial theorem and the fluctuation-dissipation theorem to the time-dependent case. (Author/SK)

Describes concrete laboratory manipulations in which time and its measurement are studied while investigating the parameters affecting the functioning of a pendulum. Also describes the origin of pendula and how cultural and historical references are integrated into laboratory practice. (Author/JN)

Compares the magnitude of the proper acceleration of a static observer in a static, isolated, spherically symmetric space-time region with the Newtonian result including the situation in the interior of a perfect-fluid star. This provides a simple physical interpretation of surface gravity and illustrates the global nature of the event horizon.…

Discusses the problem of ellipticity in the motion of the ordinary Foucault pendulum and the error caused by it. Presents a simple method of slightly modifying the force-displacement relation in such a way that precession does not result from ellipticity. (Author/SK)

Presents three simple distinct operational procedures for transforming the empirical notion of speed into a formal concept. The relationship between these three procedures and Galilean velocity and Einsteinian relativity is also included. (HM)

Describes simple modifications that will permit external triggering of certain electronic timers, thus allowing their use in experiments which require greater precision than was possible with inexpensive apparatus. (GA)

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)