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March 2017 issue of American Journal of Physics

AAPT announces that Richard Price, Massachusetts Institute of Technology, will assume the position of Editor for the  American Journal of Physics in September 2017, following the term of David P. Jackson.
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March 2017 Issue, Volume 85, No. 3

New angles on the reverse sprinkler: Reconciling theory and experiment by Joseph Beals IV. DOI: 10.1119/1.4973374

The reverse sprinkler problem popularized in Richard Feynman’s memoirs has long been a source of interest and controversy. Numerous theoretical and experimental studies have illuminated many important facets of the problem, yet disparities persist between theory and experiment. This work considers, for the first time, the spatial distribution of inertial and pressure forces on the sprinkler arms. Differences in the regions over which internal and external forces act constitute a forcecouple with different moment arms consistent with reverse rotation. Two novel sprinkler forms are presented, in principle capable of forward-only and reverse-only rotation, to elucidate specific features of this concept. It is also seen that the resulting flow-field asymmetry developed downstream from the sprinkler-arm bends supports the role of vortices in reverse sprinkler rotation by suggesting a mechanism for generating vortices in a consistent direction. The experimental challenges of isolating specific forces in light of both non-conservative forces and the influence of device design are also discussed. VC 2017 American Association of Physics Teachers.

Papers

New angles on the reverse sprinkler: Reconciling theory and experiment by Joseph Beals IV. DOI: 10.1119/1.4973374

Metamaterial hyperlens demonstration of propagation without diffraction by Simon Fleming. DOI: 10.1119/1.4972243

Why trains stay on tracks by B. Shayak. DOI: 10.1119/1.4973370

Finding the location of the instantaneous center of rotation using a particle image velocimetry algorithm by Tom Claessens. DOI: 10.1119/1.4973427

Normal modes of a defected linear system of beaded springs by Amir Aghamohammadi, M. Ebrahim Foulaadvand, Mohammad Hassan Yaghoubi, and Amir Hossein Mousavi. DOI: 10.1119/1.4972176

Radiation reaction from electromagnetic fields in the neighborhood of a point charge by Ashok K. Singal. DOI: 10.1119/1.4972246

Determination of the Sun's and the Moon's sizes and distances: Revisiting Aristarchus' method by F. Momeni, H. Papei, R. Jamshidzadeh, S. Bereliani, A. Miri more.... DOI: 10.1119/1.4967847

Project-based physics labs using low-cost open-source hardware by F. Bouquet, J. Bobroff, M. Fuchs-Gallezot, and L. Maurines. DOI: 10.1119/1.4972043

Collaborative exams: Cheating? Or learning? by Hyewon Jang, Nathaniel Lasry, Kelly Miller, and Eric Mazur. DOI: 10.1119/1.4974744

LETTER TO THE EDITOR

Maxwell's Good Fortune: The Visible Refractive Index and Static Relative Permittivity of Paraffin by Craig F. Bohren. DOI: 10.1119/1.4975385

NOTES AND DISCUSSIONS

A low-cost polarimeter for an undergraduate laboratory to study the polarization pattern of skylight by Chula P. Abayaratne, and Vibodha Bandara. DOI: 10.1119/1.4971159

BOOK REVIEWS

The Jazz of Physics by Thomas F. Jordan. DOI: 10.1119/1.4972266


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