Researchers and practitioners alike express concerns about the conceptual difficulties associated with the concepts of momentum and kinetic energy currently taught in school physics. This article presents an in-depth analysis of the treatment given to them in 44 published textbooks written for UK secondary school certificate courses. This is set…

Reports an experimental procedure for studying Einstein's theory of Brownian movement using commercially available latex microspheres and a video camera. Describes how students can monitor sphere motions and determine Avogadro's number. Uses a black and white video camera, microscope, and TV. (ML)

Provides an analysis of the forces causing the erratic motion of a knuckleball. Reveals the manner the ball should be thrown to provide maximum deflection. (Author/CP)

Presents exercises that analyze the additive property of energy. Concludes that if a body has more than one component of energy depending on the same physical quantity, the body's total energy will be the algebraic sum of the components if a linear relationship exists between the energy components and that physical quantity. (JRH)

Presents an activity that enables students to answer for themselves the question of how fast a body must travel before the nonrelativistic expression must be replaced with the correct relativistic expression by deciding on the accuracy required in describing the kinetic energy of a body. (ZWH)

Recounts the contributions of Robert Goddard from the years of 1911 to 1930 to the development of the physics of rocketry. Discusses the results of Goddard's series of rocket experiments endorsed by the Smithsonian Institute, and Goddard's claims to priority in the development of rocket theory. (MDH)

Traditional undergraduate courses in gas kinetic theory encourage the view that in all collisions between a gas atom and a surface, the angle of incidence of the gas atom equals its angle of reflection. This article illustrates and explains the incorrectness in assuming specular reflection and zero dwell time. (Author/MA)

Discusses theory, procedures, and results for an experiment which demonstrates the application of basic physics to chemical problems. The experiment involves the adiabatic process, in which polymerization carried out in a vacuum flask is compared to the theoretical prediction of the model with the temperature-time curve obtained in practice. (JN)

Describes a method, considered appropriate for presentation to undergraduate students in materials science and related courses, for the calculation of cohesive energies of the alkali metals. Uses a description based on the free electron model and gives results to within 0.1 eV of the experimental values. (Author/GS)

Discusses the physics of the "Ollie," a skateboard jump in which the skateboarder does not hold on to the board. The motion is described through three graphs that illustrate the positions of the tail of the skateboard, the center of mass, and the nose of the skateboard during a jump. (MDH)

Derives the precessional period of a Foucault pendulum without using small oscillation amplitudes. Shows that if the path of the pendulum passes through the origin, the periods for differing amplitudes are essentially the same. (GA)

Describes an experiment that generates data for calculating the ratio of molecular separation in a gas to molecular diameter. (GS)

Describes a model in which a steel ball bounces in synchronism with a vertically oscillating piston. The period of oscillation can be varied over a 3:1 range with the amplitude kept constant. As the period is increased, the ball bounces higher, contrary to the intuition of most observers. (Author/GS)

Newton's laws can be illustrated by having physics students participate in various activities while on roller skates. Several examples of such activities (including photographs) are provided. (JN)

Describes an apparatus which allows one to study the speed distribution, the gravitational distribution, and the mean free path of steel balls agitated into two-dimensional motion through collisions with the moving walls of their enclosure. (Author/GA)