An individual harmonic wave (i.e., having a single frequency and wavelength over all time and space) traveling in a loss-free medium has a single constant speed, which is equal to the magnitude of the phase velocity of the wave. However, when a set of different harmonic waves are traveling in the same direction, they interfere to form wave…

In recent years, there have been a number of articles published concerning whether or not potential energy ("PE") as defined in mechanics is invariant under Galilean transformation. This essay addresses that issue in a different, more fundamental and elegant way than has been done thus far. It recognizes that a considerable change in the…

Ideas about social justice are influenced by the ontological and epistemological assumptions of the worldview in which they are located. Since the seventeenth century, the dominant worldview in the western hemisphere has been shaped by the separatist and deterministic principles of classical Newtonian science. During the twentieth century, with…

This article analyzes and experimentally verifies the stability behavior of the equilibrium states of a conical pendulum. An analysis of the motion presents that the equilibrium states of the pendulum are determined by the pendulum angular speed. For a given pendulum length there exists a critical angular speed that determines stability…

Points near the top end of a falling rod hinged at its bottom end can fall faster than g. If a rod falls on a frictionless surface then the bottom end slides backwards and the centre of mass falls vertically with acceleration less than g. The effect was simulated by mounting a rod on wheels and filming the result with a video camera. The…

If a smooth ball is dropped vertically without spin on a smooth horizontal surface then one might expect the ball to bounce vertically without spin. If it does not then the centre of mass of the ball does not coincide with its geometric centre. An experiment is described where a billiard ball and a superball are deliberately biassed by adding a…

An a-posteriori multicentre reliability study was conducted to compare the reliability and magnitude of the maximum power (P[subscript max]) and optimal velocity (V[subscript opt]) between the force-power-velocity relationships during the leg cycle-ergometer and bench press throw exercises. The force-power-velocity relationships were determined in…

The overhead projector is perhaps passing out of use, but it is still a useful device with which to do lecture demonstrations. In my early years at Kenyon I was teaching the pre-med course, and found that the overhead projector was an ideal platform for showing the phenomena of polarized light. This note is a discussion of how I learned to use the…

A standard problem for physics students is to calculate or measure the acceleration of an object down an inclined plane. Additional information can be obtained by measuring the angular acceleration as well as the linear acceleration. An experiment is described where a billiard ball was filmed as it rolled down an inclined plane at different…

Many readers of this journal are probably familiar with calls from governmental, business, and educational authorities to expand and improve the preparation of science teachers, with a particular focus on the shortage of highly qualified physics teachers. It may seem as if this problem has been around forever, and in fact similar expressions of…

The question of whether Faraday's flux law is universal or whether there are exceptions has long been controversial. This discussion seemed to have recently concluded in favor of the generality of Faraday's Flux Law. The present article raises this question again with the aid of some rather simple measurements carried out on a Faraday generator.…

Numerosity perception has been studied for at least 150 years and its psychophysics have been well characterized by experimental work. However, the origins of many of its key properties remain obscure. For instance, people estimate the numerosity of small sets (up to four) much more rapidly and accurately than larger sets; people tend to…

Knowledge about the interior density distribution of a planetary body can constrain geophysical processes and reveal information about the origin and evolution of the body. Properties of this interior distribution can be inferred by analyzing gravity acceleration data sampled by orbiting satellites. Usually, the gravity data is complemented with…

Here is presented an interesting problem that can be used to introduce students to a variety of physics topics including non-inertial frames and frictional forces, rotational dynamics, and damped oscillations; the normal force also appears, but not in its usual guises. The problem is a generalized version of problem 3.34 presented in the…

A good paradox has the viewer confused, but the best paradoxes lead the viewer to try to understand what is happening. One of the author's favorites is the hydrostatic paradox, in which a short and slender column of water supports a relatively enormous weight. He describes the paradox using an illustration of a student who weighs 60 points stands…