Purpose: To assess changes in criterion validity when modifying cut-points for use in different epoch lengths. Method: Simulated free-living data came from 42 adolescents (2-hr each) and 29 adults (6-hr each) wearing a hip-worn accelerometer and portable indirect calorimeter (Cosmed K4b[superscript 2]). K4b[superscript 2] data were classified as…

The Michelson interferometer is one of the key experiments in modern physics when it comes to the topic of interference (Box 1). Experiments using interferometry have a high historic relevance as well as uses in current areas of research (quantum erasers, gravitational wave detection) and are used in higher education. Because of the high cost of…

This paper is intended to foster conversations about stereotypes, prejudice, and our day-to-day work in the classroom. The focus is on sexism and how it can affect our teaching, particularly looking at physics textbooks. Maybe you are already familiar with debates around feminist movements, gender studies, patriarchy, performance, and all of those…

In early January 2018, after days of subfreezing temperatures, a 20 m waterfall became mostly frozen with supercooled water pouring over the top of the frozen parts of the fall. A video was taken of the waterfalls and supercooled turbulent water flowing on the frozen surface as it turned into frazil ice right before our eyes. Frazil ice consists…

We propose an experimental analogy to verify Kepler's second law using a spherical pendulum. We made a movie of a closed elliptical orbit of the pendulum and extracted the data position using the Tracker software. Analyzing the data, we measured the areas that the position vector sweeps showing the validity of Kepler's second law.

This work presents an experiment that seeks to simulate human color vision through electronic components in an attempt to build, together with the students, a cybernetic 'eye'. The limitation of the cybernetic eye developed here in relation to the standard human chromatic vision, which makes it a 'colorblind eye', is an argument to be explored by…

When we travel in a train moving at a certain velocity, we observe the stationary objects outside are moving backwards. These stationary objects seem to move due to a relative velocity. Consider that the stationary object outside the train is a man standing on the stationary floor watching a woman moving on a train. The woman on a train will see…

A new device for teaching the physics of sound, specifically demonstrating the wavelengths of standing sound waves, is here described. I define a "Lincoln's Tube" as any hollow tube that uses lights (LEDs typically) to demonstrate the presence of sound standing waves. The name is chosen intentionally to recall a Ruben's Tube or a Kundt's…

Semiconductor devices, usually made from silicon wafers, are present in the electronic gadgets that we use on a daily basis. In an introductory physics class, the textbook usually devotes a few pages to these devices and moves on. As a result, students may readily forget the material or fail to see how it relates to their lives. A solution is to…

Heat transfer is a phenomenon well known from everyday life. It is intuitively connected to the properties of materials, that is, to the physics concept of thermal conductivity relevant for cooking or maintaining the constant temperature in rooms, even without being familiar to the underlying physics. However, measurement of thermal conductivity…

Keto-enol tautomerism is a fundamental concept that examines the migration of a proton between two constitutional isomers, the keto and enol tautomer. Many experiments have been proposed to understand the concept behind Meyer's Rule, which states that the keto tautomer is favored as the solvent polarity increases. However, all the experiments have…

Our aim in this paper is to describe an opportunity for physics students and faculty to learn about an environmental issue of much current interest: the quantification, or footprint analysis, of carbon dioxide (CO[subscript 2]) and reactive nitrogen emissions. These can originate from human activities such as energy use, food consumption, and…

This note is about 1000 words in length. We have been taught that this much information is contained in a single picture. But, Fig. 1 is so rich that four separate ideas can be obtained from it! The figure appears in "The Boy's Playbook of Science" by John Henry Pepper. Pepper tells us that this shows an "assistant standing on the…

The purpose of this study is to reduce ethics violations such as tricking and cheating that may occur in the offline assessment of undergraduate level Physics-II (Electricity) course subjects. The study is significant for the reliable and ethical evaluation of the Internet and computer-based educational process. Thirty-eight pre-service teachers…

This chapter illustrates the main warning signals that could help us to detect the flaws of an explanation in physics: internal contradiction (two examples); direct contradiction of a law of physics (one example); indirect contradiction of a law of physics (one example); logical incompleteness of an explanation (three examples); overgeneralization…