These brief summaries are designed to help readers easily see which articles will be most valuable to them. The online version contains links to the articles.

Regular readers will note the temporary increase in the length of the journal. Since mid-May, submissions have been up by about 35%. We live in interesting times.

Sanjoy Mahajan

https://doi.org/10.1119/10.0002140

This paper presents a simple model for the energy used in flight, understandable with only introductory mechanics. The lift and drag forces combine to yield a speed at which efficiency is maximized.

D. Taylor, H. Smaje, and P. Moriarty

https://doi.org/10.1119/10.0001700

Instructions are given for the low-cost construction of a macroscopic analog of an atomic force microscope that demonstrates many of the principles of AFM microscopy, using LEGOs, magnets and an Arduino microcontroller. The construction is a multifaceted laboratory experience for advanced undergraduates, and the device is useful for illustrating AFM in courses and in outreach.

George H. Rutherford, Zach D. Mobille, Jordan Brandt-Trainer, Rosangela Follmann, and Epaminondas Rosa, Jr.

https://doi.org/10.1119/10.0001072

A circuit that mimics the action potential and ion channels of a neuron is useful for both pedagogical and research purposes. The article presents a simple implementation of such a circuit, requiring only basic background in electronics and the physics of neurons.

Vera Margoniner, Jérôme Bür, and Matthew Block

https://doi.org/10.1119/10.0001699

Methods and results are presented from experiences using student learning assistants in active learning approaches to calculus-based mechanics at a public university, with evidence of greater learning gains. This work may be of interest to those considering changes in teaching methods.

Jacob Emil Mencke, Mirko Salewski, Ole L. Trinhammer, and Andreas T. Adler

https://doi.org/10.1119/10.0001659

The motion of spinning sports balls is studied using a combination of analytical, numerical, and experimental techniques. Motion in both vacuum and air is considered, as well as flight and bouncing motion. Appropriate for undergraduates learning about projectile motion.

Maximillian Hart and Mark G. Kuzyk

https://doi.org/10.1119/10.0001686

Mobile phone videos of pool-ball collisions yield rich data that can be analyzed in terms of not only the conservation of energy and momentum but also dissipative forces. Such experiments outside of campus can serve as a useful alternative when in-lab experiments are not practical.

Vladimir V. Ivchenko

https://doi.org/10.1119/10.0001696

By considering the torques from the force applied to a helical spring, a relationship of force and spring elongation is derived that goes beyond Hooke's law. This work can help undergrads beyond the first year appreciate nonlinearity.

L. N. Gonçalves, J. Fernandes, A. Ferraz, A. G. Silva, and P. J. Sebastião

https://doi.org/10.1119/10.0001660

The physical pendulum is studied with consideration of details related to hysteresis, entrainment of air mass, etc. Of particular interest is the use of fractional derivatives to represent memory effects. The material is most appropriate for advanced undergrads.

M. Rushka and J. K. Freericks

https://doi.org/10.1119/10.0001702

This paper presents a full algebraic derivation of the wavefunctions of the simple harmonic oscillator, appropriate for either undergraduate or graduate classes in quantum mechanics. This completely algebraic approach avoids introducing derivative operators and solving differential equations. A historical account of the operator method for the simple harmonic oscillator is also given.

Asadullah Bhuiyan and Frank Marsiglio

https://doi.org/10.1119/10.0001703

Probability densities of quantum states ought to be gauge invariant, but this invariance can be hard to see. Eigenstates in both circular and square quantum dots in perpendicular magnetic fields are used to explore this gauge invariance, in a paper appropriate for upper-level undergraduate and introductory graduate level quantum mechanics instruction.

Edgar Perez, Colleen Werkheiser, Alex Striff, and Lucas Illing

Delay circuits enable the exploration of nonlinear effects and chaos, but existing circuits that can provide ∼100 ms delays are expensive or limited to AC signals. This paper, appropriate for advanced undergraduates, gives plans for a programmable delay circuit based on an Arduino Due and illustrates its use in exploring circuit dynamics.

Eduardo Gonzalez, Seong J. Park, and David M. Laman

https://doi.org/10.1119/10.0001752

Undergraduates can measure and correct for instrument response, allowing nanosecond luminescence lifetimes to be measured with standard equipment in the advanced laboratory.

F. M. S. Lima

https://doi.org/10.1119/10.0001694

For the energy levels in a finite quantum square well, an approximation method is presented that is accurate even for very deep or shallow wells, only requires a pocket calculator, and is appropriate for an introductory quantum course.

Arseni Goussev

https://doi.org/10.1119/10.0001773

A recent AJP paper had shown that the flow of probability for a Gaussian wave packet can be in the direction opposite to that of the wave packet itself. In an analysis appropriate for a junior-level quantum mechanics course it is shown that this quantum effect is analogous to a classical effect.