October 2017 AJP cover

October 2017 Issue, Volume 85, No. 10

Unmixing demonstration with a twist: A photochromic Taylor-Couette device

The featured article describes an updated version of the famous Taylor-Couette flow reversibility demonstration. The viscous fluid confined between two concentric cylinders is forced to move by the rotating inner cylinder and visualized through the transparent outer cylinder. After a few rotations, a colored blob of fluid appears well mixed. Yet, after reversing the motion for the same number of turns, the blob reappears in the original location as if the fluid has just been unmixed. The use of household supplies makes the device inexpensive and easy to build without specific technical skills. The device can be used for demonstrations in fluid dynamics courses and outreach activities to discuss the concepts of viscosity, creeping flows, the absence of inertia, and time-reversibility.





A few words from the new editor by Richard H. Price.  DOI: 10.1119/1.5000807

Guest Editorial

Is college teaching as a calling being impacted by research? by J. C. Sanders.  DOI: 10.1119/1.4997024

Letter to the Editor

The Buron—The Elementary Particle of Bureaucracy by Dieter Schumacher. DOI: 10.1119/1.5000803


Resource Letter FCA-1: Frequency Combs and Applications by Dylan C. Yost. DOI: 10.1119/1.4997164

Incorporating current research into formal higher education settings using Astrobites by Nathan E. Sanders, Susanna Kohler, Chris Faesi, Ashley Villar, and Michael Zevin. DOI: 10.1119/1.4991506

Solutions of the Schroedinger equation for piecewise harmonic potentials: Remarks on the asymptotic behavior of the wave functions by Francisco D. Mazzitelli, Martín D. Mazzitelli, and Pedro I. Soubelet. DOI: 10.1119/1.4994808

Measurement of gravitational time dilation: An undergraduate research project by M. Shane Burns, Michael D. Leveille, Armand R. Dominguez, Brian B. Gebhard, Samuel E. Huestis more...DOI: 10.1119/1.5000802

Simulations in quantum tunneling by Kevin Smith and Guy Blaylock. DOI: 10.1119/1.4991367

Two and three particles interacting in a one-dimensional trap by MengXing Na, and Frank Marsiglio. DOI: 10.1119/1.4985063

The physics of a popsicle stick bomb by Jérémy Sautel, Andréane Bourges, Aude Caussarieu, Nicolas Plihon, and Nicolas Taberlet. DOI: 10.1119/1.5000797


Correction: Cover image caption [Am. J. Phys. 85(7), back cover (2017)] by David P. Jackson. DOI: 10.1119/1.5000838

Generalization of parallel axis theorem for rotational inertia by A. R. Abdulghany. DOI: 10.1119/1.4994835


Unmixing demonstration with a twist: A photochromic Taylor-Couette device by Enrico Fonda, and Katepalli R. Sreenivasan. DOI: 10.1119/1.4996901


A Tale of Seven Scientists and a New Philosophy of Science by Michael D. Gordin. DOI: 10.1119/1.4996864

True Genius. The Life and Work of Richard Garwin, The Most Influential Scientist You've Never Heard Of by Cameron Reed. DOI: 10.1119/1.5001934


American Journal of Physics 85, 803 (2017); http://doi.org/10.1119/1.5000378


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