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)

Discusses new studies in neutron physics within the last decade, such as ultracold neutrons, neutron bottles, resonance behavior, subthreshold fission, doubly radiative capture, and neutron stars. (MLH)

Shows how to include the dissipative forces of classical mechanics in quantum mechanics by the use of non-Hermetian Hamiltonians. The Ehrenfest theorem for such Hamiltonians is derived, and simple examples which show the classical correspondences are given. (MLH)

Outlines a mathematical paradox obtained when calculating the dimensions of a hydorgen molecule using relativistic wave mechanics. (MLH)

Presents an intuitive derivation of the point reactor equations followed by formulation of equations for inverse and direct kinetics which are readily programmed on a digital computer. Suggests several computer simulations involving the effect of control rod motion on reactor power. (MLH)

Summarizes the conceptual development of the notion of force historically and suggests appropriate analogies, limiting case analyses, thought experiments, and imagistic representations that can be used in high school physics classrooms. (DDR)

Describes a system of interactive astronomy whereby nonscience students are able to acquire their own images from a room remotely linked to a telescope. Briefly discusses some applications of Charge-Coupled Device cameras (CCDs) in teaching free fall, projectile motion, and the motion of the pendulum. (JRH)

Shows that the conventional wisdom about the extreme inaccuracy of stopwatch measurements during the acceleration and free fall of objects is mistaken. (ZWH)

Presents an application of fundamental principles of mechanics for an isolated system in solving problems related to rocket velocity and exhaust elements. (JRH)

Presents a simple but effective experiment that uses ultrasonic transducers and some basic electronics to study the speed of sound using the Doppler effect. Eliminates the noise problems associated with most sound experiments. Discusses the theory, and describes the apparatus and procedure. (JRH)