Following a short review of the history of cosmic-ray astrophysics and a discussion of the accumulated data, pointing to the need for isotope measurement, the theory of heavy-element nucleosynthesis is reviewed to provide a basis for the interpretation of the cosmic-ray data. (Author/JN)

Discusses how the wheel works. The inherent mechanical advantage of wheel-and-axle system is that it reduced the distance the load-bearing surfaces have to slip relative to one another when the whole apparatus advances some given distance reducing (with leverage) the force needed to propel the system. (Author/JN)

The lack of parallelism between the force and acceleration vectors has several apparently paradoxical consequences that have been recently examined. This article uses a different and more general mode of analysis than previous authors to derive quite general, rather than particular, results. (Author/SK)

Describes a model for inelastic scattering obtained by suitably generalizing scattering from a square well. The generalization introduces matrices into the quantum-mechanical scattering equations, which may be solved exactly to give an explicit expression for the scattering matrix. Discusses the results it predicts for a simple example. (Author/SK)

This article is a preview of the book, "Physics News in 1980." Five research areas are reviewed: high energy particle accelerators, fusion reactors, solar cells, astrophysics, and gauge theories. (Author/DS)

Examines several parameters concerning the performance of tennis rackets, such as the location of the center of percussion, the time of contact, the period of oscillation of the tennis racket, and the coefficient of restitution of a tennis ball. The purpose is to design a racket with improved playing characteristics. (Author/GA)

Suggests an alternative system of measurement to be used in engineering, which provides theoretical insight and leads to definitions of dual and analogous physical quantities. The system is based on the notion that the dimensional product of three fundamental quantities should be energy. (GA)

Modifies and expands on the treatment of the twin paradox by solving the gravitational field equations and geodesic equations of motion in the traveling twin's reference frame, thus determining the time elapsed on the Earth during the periods of acceleration. (Author/GA)

Presents a method to solve differential equations of free damped oscillators, so that general (periodic and aperiodic) solutions can be obtained, solely on the basis of elementary knowledge of differential and integral calculus and avoiding the use of complex functions. (GA)

Investigates the change in weight associated with the electrostatic potential energy for a system of two point charges supported side by side against a weak gravitational field. (Author/GA)

Explains properties of the Airy packet that show that quantum wave functions correspond to a family of orbits and not to a single particle. Introducing the Airy packet into elementary quantum mechanics courses is recommended. (HM)