This simple experiment uses an unusual graph straightening exercise to confirm the parallel axis theorem for an irregular object. Along the way, it estimates experimental values for g and the moment of inertia of a tennis racket. We use Excel to find a 95% confidence interval for the true values.

This paper is the second in the series of LED-dedicated papers that have a goal to systematically investigate the use of LEDs in a general physics course. The first paper, published in the February 2014 issue, provided an overview of the course units where LEDs can be used and suggested three different ways of utilizing LEDs in an introductory…

On Aug. 13, 2011, at 8:45 p.m. country music fans were eagerly awaiting the band Sugarland to make its entry onto the main stage at the Indiana State Fairgrounds. Also competing for the fans' attention was an approaching storm. Sugarland never made their entrance. At 8:49 p.m. the stage rigging was hit by 59 mile/h (94 km/h) winds causing it…

One of the basic ideas when studying science is that matter is composed of particles (atoms or molecules) and these are in a constant state of agitation. In the solid or liquid state the molecules are attracted to each other, while in the gaseous state they have sufficient energy to overcome the forces of cohesion and can move away from one…

The ripple tank is one of the physics education devices most appreciated by teachers and students. It allows one to visualize various phenomena related to wave physics in an effective and enthralling way. Usually this apparatus consists of a tank with a transparent bottom that is filled with a thin layer of water. A source of light illuminates the…

By superimposing two sound waves of the same wavelength, propagating in the opposite direction, we can create an intensity pattern having a characteristic scale equal to half a wavelength: it is the diffraction limit. Recently a group from the Institut Laue-Langevin in Paris has shown that it is possible to go beyond this limit by focusing sound…

We cannot hope for a new generation of scientists and engineers if we don't let our young students take ownership of their scientific and engineering explorations, if we don't let them enjoy the hands-on cycle of design and production, and if we don't let them implant their creativity into a technologically friendly environment.…

The leading theory for the origin of the Moon is the giant impact hypothesis, in which the Moon was formed out of the debris left over from the collision of a Mars sized body with the Earth. Soon after its formation, the orbit of the Moon may have been very different than it is today. We have simulated the phases of the Moon in a model for its…

It is a known fact that it takes a greater effort to run on an exercise treadmill when it is inclined with positive slope than when it is in a horizontal position. The reason seems simple: walking on an inclined treadmill is somehow equivalent to walking up a hill with the same inclination; when we walk up a hill, our own weight does negative work…

Understanding the inverse square law, how for example the intensity of light or sound varies with distance, presents conceptual and mathematical challenges. Students know intuitively that intensity decreases with distance. A light source appears dimmer and sound gets fainter as the distance from the source increases. The difficulty is in…

In this column, we have previously presented various examples of how physical relationships can be examined by analyzing acoustic signals using smartphones or tablet PCs. In this example, we will be exploring the acoustic phenomenon of small beats, which is produced by the overlapping of two tones with a low difference in frequency ?f. The…

Given that transportation is an essential topic in any Physics and Society or Energy course, it is necessary to have useful statistics on transportation in order to have a reasoned discussion on this topic. And a major component of the transportation picture is the automobile. This paper presents updated transportation statistics for American…

Mobile device accelerometers are a simple and easy way for students to collect accurate and detailed data on an amusement park ride. The resulting data can be graphed to assist in the creation of force diagrams to help students explain their physical sensations while on the ride. This type of activity can help students overcome some of the…

Energy is a topic that is often treated as an accounting process-a number that students are asked to calculate, but that is not particularly meaningful in itself. When we try to ascribe meaning to this number ("an ability to do work," for example), we are met with caveats and hedges. As Feynman notes when lecturing on the conservation of…

Authors of physics textbooks frequently use the deflection of a thin, vertically falling water jet by a charged balloon, comb, or rod as a visually appealing and conceptually relevant example of electrostatic attraction. Nevertheless, no attempts are made to explore whether these charged bodies could cause visible deformation of a horizontal water…