- Some effective demonstrations have been presented in recent issues of The Physics Teacher. Check out the use of a water-filled balloon to discuss buoyant force on page 428 of the October 2012 issue, and the counterintuitive behavior of series versus parallel springs on page 359 of the September 2012 issue.
- A compact proof that M12 must equal M21 for the mutual inductances of two coupled circuits is provided by Dake Wang on page 840 of the September 2012 issue of the American Journal of Physics. I also enjoyed learning about the paradox of a floating candle that does not get extinguished on page 657 of the August 2012 issue, and the energy efficiency of the various systems in a car on page 588 of the July 2012 issue. The discussion on page 519 of the June 2012 issue of why shear is omitted from our standard discussions of divergence, gradient, and curl also intrigued me.
- Connect a smaller spherical balloon to a larger one with a tube. It is not always the case that the smaller one will get smaller and the bigger one get bigger. See the experimental results and discussion on page 392 of the July 2012 issue of Physics Education. An aluminum soda can pull tab is floated on the surface of a glass of water. An electrostatically charged rod is brought near the tab. Does the tab move toward the rod, away from it, or stay still? See page 644 of the September 2012 issue for the surprising answer. Also check out the discussion of the volume of conical glasses and oval spoons on pages 502–504 of the July 2012 issue: half full is nowhere near half height! The journal can be accessed at http://iopscience.iop.org/journals.
- The same webpage also gives a link to the European Journal of Physics. On page 1111 of the September 2012 issue, there is a discussion of particles sliding off the surfaces of arbitrarily shaped surfaces (not necessarily hemispherical as in the usual textbook case), with or without kinetic friction. Also see the discussion of the classic problem of whether or not one should run in the rain to keep as dry as possible on page 1321, and an analysis of the tumbling toast problem on page 1407 of the same issue. Finally, there is a good review of theoretical models and comparison to experimental measurements for falling U-shaped or piled-up chain systems on page 1007 of the July 2012 issue.
- The June 2012 issue of the Journal of Chemical Education has a short but provocative discussion of how to define elements in contrast to compounds on page 832, and an article about how lightsticks work on page 910. Peter Loyson argues on page 1095 of the August issue that Galileo did not invent the Galilean thermometer. I was also sufficiently intrigued by the discussion of the laws of thermodynamics applied to open systems on page 968 of the July issue to write my own analysis at http://usna.edu/Users/physics/mungan/Scholarship/OpenSystems.pdf.
Carl Mungan is an Associate Professor of Physics at the United States Naval Academy.
Disclaimer–The articles and opinion pieces found in this issue of the APS Forum on Education Newsletter are not peer refereed and represent solely the views of the authors and not necessarily the views of the APS.