This is the renamed “editorial blurbs,” designed to help readers easily see which articles are most likely to be most useful and appropriate for them. Note that the online version now contains links to the articles.
A strange spring system
Sanjoy Mahajan
When you don’t have much intuition for a solution, how can you check your guesses? This paper suggests three approaches, all worthy of inclusion in your physics toolkit.
Electromagnetic radiation and the self-field of a spherical dipole
Masud Mansuripur and Per K. Jakobsen
For a spherical dipole, an exact expression for the self-field (i.e., the electric field responsible for radiation resistance) can be found by a straightforward solution of Maxwell's equations, appropriate for advanced undergraduate or graduate students.
The paradox of the tight spiral pass in American football: A simple resolution
Richard H. Price, William C. Moss, and T. J. Gay
In a tight spiral pass, the long axis of an American football remains nearly parallel to the trajectory. Using simple assumptions, one can approximate the rotational dynamics of the symmetry axis, and thus understand the motion. Appropriate for undergraduate-level mechanics classes.
Multiple approaches to incorporating scattering states in non-degenerate perturbation theory
Don C. Colladay and John Eric Goff
Three different approaches are given for incorporating scattering states in non-degenerate perturbation theory. An example consisting of a perturbed square well is worked out in detail, at a level appropriate for undergraduate students in quantum mechanics.
Plasma waves in a different frame
A. Macchi
Analyzing plasma waves in a reference frame moving with the plasma phase velocity provides a relatively simple derivation of conditions for the breaking of waves. The paper serves as an introduction to plasma physics and is suitable for undergraduates with a basic knowledge of special relativity and electrodynamics.
A first-year research experience: The freshman project in physics at Loyola University Chicago
Jonathan Bougie, Asim Gangopadhyaya, Sherita Moses, Robert D. Polak, and Gordon P. Ramsey
The Freshman Projects program in Physics at Loyola University Chicago has been in place for over twenty years, and has coincided with significant growth in the department. This paper describes this program and makes suggestions for adoption of similar programs at other institutions.
Laser diode coherence
Tim Gfroerer and Morgan Bergthold
A Michelson interferometer is used to study the emission properties of a laser diode, ranging from broadband emission at low operating currents to monochromatic emission at high operating currents, and also demonstrates the inverse relationship between coherence length and spectral bandwidth. Appropriate for an undergraduate-level optics class.
Numerical and Analytical Study of the Bound States of the −α/x2 Potential
Thanh Xuan Nguyen and F. Marsiglio
Quantum bound states are calculated for the attractive −α/x2 potential by adopting a finite cutoff in the potential near x = 0. Both analytical and numerical solutions can be used, making this a nice example for an undergraduate research project.
The paradox of the tight spiral pass in American football: Insights from an analytic approximate solution
Richard H. Price
An accurate closed-form analysis of the football’s trajectory is given, based on the assumption that there are only small differences in the directions of the axis, the trajectory, and the angular momentum.
Comment on “A computer model of classical rolling friction” [Am. J. Phys. 87, 720–728 (2019)]
Keith Zengel
This short paper, appropriate for a first mechanics course, comments on the forward shift of the normal force, and emphasizes the role of static friction in rolling motion.
An asymmetrical double torsion pendulum for studying coupled harmonic motion
Yuntian Wang, Xintong Duan, Mingzhen Shao, Cailin Wang, and Huan Zhang
A "double torsion pendulum" allows exploration of coupled systems with extra insights provided by asymmetry. Both theory and experimental advice is given for a lab well suited to the first undergraduate mechanics course.
Computational physics projects related to Weyl's problem
Isaac Bowser, Joshua Kiers, Ken Kiers, and Erica Mitchell
Weyl’s theorem predicts that, in the limit of large wavenumbers, the density of states depends on the volume but not on the shape. This paper presents computational projects that allow students to calculate corrections to Weyl’s theorem for three geometries, providing an effective means to introduce computation into undergraduate courses in quantum mechanics, statistical mechanics, or solid-state physics.