This paper focuses on the determination of the final equilibrium state when two ideal gases, isolated from the exterior and starting from preset initial conditions, interact with each other through a piston. Depending on the piston properties, different processes take place and also different sets of equilibrium conditions must be satisfied. Three…

We present a study of the ascending vertical motion of a self-propelled body under a uniform gravitational field suffering the action of two different types of air friction forces: linear on the velocity, which is valid for slowly moving bodies, and quadratic on the velocity. We study the special case where the thrust force is a decreasing…

The observation of peculiar light patterns produced by reflection from a water surface perturbed by falling droplets is reported. The phenomenon is analysed in some detail, with a simplified model of a surface wave packet. A simple experiment reproducing the phenomenon in the laboratory is presented, also showing evidence of pattern distortions…

We solve for the motion of an object with initial velocity v[subscript 0] and subject only to the combined drag of forces linear and quadratic in the velocity. This problem was treated briefly by Newton, after he developed a theoretical argument for the quadratic term, which we now know is characteristic of turbulent flow. Linear drag introduces a…

Light from a rough sample surface illuminated with a laser consists of a speckle pattern. If the surface evolves with time, the pattern becomes dynamic, following the activity of the sample. This phenomenon is used both in research and in industry to monitor processes and systems that change with time. The measuring equipment generally includes…

The reciprocal lattice is derived through the Fourier transform of a generic crystal lattice, as done previously in the literature. A few key derivations are this time handled in detail, and the connection with x-ray diffraction is clearly pointed out. The Ewald sphere is subsequently thoroughly explained and a few comments on its representation…

We show the impossibility of harvesting power from rotational motions by devices attached to the rotating object. The presentation is suitable for students who have studied Lagrangian mechanics. (Contains 2 figures.)

Introductory calculus-based physics textbooks state that electromagnetic waves are transverse and list many of their properties, but most such textbooks do not bring forth arguments why this is so. Both physical and theoretical arguments are at a level appropriate for students of courses based on such books, and could be readily used by…

The predator-prey relationship is one of the most recognizable and well-studied animal relationships. One of the more striking aspects of this relationship is the differential natural selection pressure placed on predators and their prey. This differential pressure results from differing costs of failure, the so-called life-dinner principle. If a…

We investigate the interplay between mathematics and physics resources in intermediate mechanics students. In the mechanics course, the selection and application of coordinate systems is a consistent thread. At the University of Maine, students often start the course with a strong preference to use Cartesian coordinates, in accordance with their…

A laboratory-based exercise that demonstrates mechanisms underlying leaf degradation in streams. Students examine the effects of "leaf conditioning" on the feeding behavior of invertebrate shredders. The exercise is completed in two sessions and can be adapted to both high school and college levels.

The rapid advances in technology and scientific knowledge in modern society increases the need for a workforce with an understanding of technology and critical thinking skills College graduates are entering the working world without the critical thinking skills and ability to apply the scientific knowledge gained during their undergraduate…

One of the most known phenomena in physics is the Hall effect. This is mainly due to its simplicity and to the wide range of its theoretical and practical applications. To complete the pedagogical utility of the Hall effect in physics teaching, I will apply it here to determine the Faraday constant as a fundamental physical number and the number…

A general mathematical treatment for chemical systems is described that might help students to better understand the real scope of the mathematical equations. The extent to which an equation acceptably describes a chemical system is determined from the limiting values of practical chemical variables and the concordance value defined by given…

The study demonstrates the induction of one-dimensional standing waves, called "natural-harmonics" on a guitar to provide a unique tone. The analysis shows that a normally complex vibration is composed of a number of simple and discrete vibrations.