Recently, the editor remarked to me that physics departments that offered a PhD with a specialization in Physics Education Research (PER) seemed to graduate more bachelor's degree recipients than those physics PhD departments that did not have the specialization. I was not convinced. That led to quite a bit of discussion between us. He compiled a…

Every time I have to jack up my car, I am a bit surprised by how slowly the scissors jack works the higher I raise it, and close to maximum height I need very little force to turn the crank. This agrees well with the principle of simple machines. Since I have to jack up my car at least twice a year to change between winter tires and summer tires,…

After many years of confusion, thermal performance of sleeping bags has now been quantified and unified using expensive test techniques. Based on Newton's law of cooling, we present a simple inexpensive test and model to check manufacturers' claims on the temperature performance of a range of modern sleeping bags.

A spectrogram of a singer's vibrato presents a striking way to introduce students to frequency, Fourier spectra, and modulation. Vibrato is discussed from the perspectives of the physicist and the musician. A dramatic spectrogram is included where coauthor soprano Michel suppresses her vibrato so that acoustical characteristics can be compared to…

For over half a century, starting around 1960, physics education was put under the intellectual microscope of a London-based university lecturer--Dr John Warren. His scrutiny of physics textbooks and examination papers in particular led him to conduct a sustained assault on error, ambiguity and lack of rigour in the presentation of our subject.…

Students are better able to understand Newton's first law when they build from their own personal experiences of bicycling, skateboarding, or riding in a car. Most have experienced a tumble when their skateboard or bicycle comes to an abrupt stop. Alternately in a car, your body continues moving when the brakes are applied and you feel the force…

Understanding Physics is a great end in itself, but is also crucial to keep pace with developments in modern technology. Wireless power transfer, known to many only as a means to charge electric toothbrushes, will soon be commonplace in charging phones, electric cars and implanted medical devices. This article outlines how to produce and use a…

Acoustic levitation uses a resonant ultrasonic standing wave to suspend small objects; it is used in a variety of research disciplines, particularly in the study of phase transitions and materials susceptible to contamination, or as a stabilization mechanism in microgravity environments. The levitation equipment used for such research is quite…

Paul Hewitt's "Figuring Physics" in the Feb. 2016 issue asked whether it would take a larger velocity change to stop a satellite in a circular orbit or to cause it to escape. An extension of this problem asks: What "minimum" velocity change is required to crash a satellite into the planet, and how does that compare with the…

Virtual images are often introduced through a "geometric" perspective, with little conceptual or qualitative illustrations, hindering a deeper understanding of this physical concept. In this paper, we present two rather simple observations that force a critical reflection on the optical nature of a virtual image. This approach is…

Physics can be a weighty subject, full of substance and gravitas. It is therefore perhaps entirely reasonable that a central topic of the discipline is mass. But what is mass, really? What is the origin and nature of this most essential feature of the world around us? And are there any surprises to be had as we dig deeper into that question? In…

The butterfly theorem is proved by assigning point masses to the four vertices of the wings and using the distributive property of the mass centre of a mechanical system.

The measurement of the speed of sound in air with the resonance tube is a popular experiment that often yields accurate results. One approach is to hold a vibrating tuning fork over an air column that is partially immersed in water. The column is raised and lowered in the water until the generated standing wave produces resonance: this occurs at…

There are several variations of resonance laboratory activities used to determine the speed of sound. This is "not" one of them. This activity uses the resonance tube idea to teach "resonance," not to verify the speed of sound. Prior to this activity, the speed of sound has already been measured using computer sound-sensors and…

Self-diagnosis (SD) activities require students to self-diagnose their solutions to problems that they solved on their own. This involves identifying where they went wrong and then explaining the nature of their errors--why they went wrong--aided by some form of support. Worked examples (WEs) are often used to support students in SD activities. A…