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Oct 2008

Volume 46, Issue 7, pp. 388-448

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2008 Distinguished Service Citations Awarded to Dean Baird, Anne Cox, Harry Manos, Karen Jo Matsler, Steve Shropshire, and Richard Zitto

Harvey S. Leff, 2007 AAPT President

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 388

Online Publication Date: Sep 2008

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01.10.Cr Announcements, news, and awards
01.60.+q Biographies, tributes, personal notes, and obituaries
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Correction to the paper “The circle of Apollonius and its applications in introductory physics,” Phys. Teach. 46, 104–108 (Feb. 2008)

Michael B. Partensky

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 392

Online Publication Date: Sep 2008

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01.40.gb Teaching methods and strategies
99.10.Cd Errata
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FROG DROP

Paul Hewitt

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 394

Online Publication Date: Sep 2008

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01.50.Rt Physics tournaments and contests
01.50.Kw Techniques of testing
01.55.+b General physics
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Measurement of g Using a Flashing LED

T. Terzella, J. Sundermier, J. Sinacore, C. Owen, and H. Takai

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 395 | Cited 1 time

Online Publication Date: Sep 2008

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In one of the classic free-fall experiments, a small mass is attached to a strip of paper tape and both are allowed to fall through a spark timer, where sparks are generated at regular time intervals. Students analyze marks (dots) left on the tape by the timer, thereby generating distance-versus-time data, which they analyze to extract the acceleration due to gravity g with good results. The apparatus, however, is cumbersome and often frustrating for students.1 High-tech versions of this experiment are done with an object dropped and followed by a motion sensor connected to a computer. The sensor relies on ultrasonic ranging to record distance and time data, which may then be displayed graphically. Students inspect the graphs to determine the value of g. Although the results are excellent, the emphasis on the computer's ability to collect and analyze data leaves little analysis for the students to perform.2 Furthermore, neither technique gives an intuitive display of what is happening. The motivation for our work was to overcome these issues by developing an innovative method for measuring g. In our version of the experiment, students drop a flashing LED at a known frequency and record its trajectory using long exposure photography with a digital camera. Proper choice of flashing LED timing parameters produces an image that allows for an accurate measurement of g and at the same time helps to explain what happens during free fall. The experiment remains high-tech in the sense that students learn to use updated equipment to record data and to carry out the analysis.
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01.50.My Demonstration experiments and apparatus
01.50.Pa Laboratory experiments and apparatus
01.40.J- Teacher training
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A Cool Sport Full of Physics

Alain Haché

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 398 | Cited 2 times

Online Publication Date: Sep 2008

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Of all sports, ice hockey is possibly the one with the widest array of physics elements in it. The game provides many examples that can bring physics to life in the classroom. Ice hockey (or just “hockey” as many Canadians would say) sees athletes sliding on ice at high speeds and in various ways, shooting and slapping pucks, and colliding against each other. The interaction between the skate blade and the ice is a problem of great physical complexity. The question “Why is ice so slippery?” has puzzled generations of scientists and, surprisingly, clear answers have come relatively recently. There is even some optics involved in hockey: how many sports are watched behind tempered glass (or Plexiglas) windows? The optical and mechanical properties of these materials are worth a physics classroom discussion. In this paper, I will review a few topics discussed at length in my book The Physics of Hockey.1,2 Interested readers may also find additional articles on our website.3
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01.55.+b General physics
01.40.gb Teaching methods and strategies
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The Surprising Effectiveness of College Scientific Literacy Courses

Art Hobson

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 404 | Cited 4 times

Online Publication Date: Sep 2008

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Research by Jon Miller, professor of Interdisciplinary Studies and director of the International Center for Scientific Literacy at Michigan State University, shows that the U.S. scientific literacy course requirements for nonscience college students pull the United States into second place in international rankings of adult scientific literacy. This despite the poor science scores of U.S. primary and secondary school students as compared with other nations. The far lower adult scientific literacy rankings of most European nations and other industrialized nations appear to be due to the lack of any such college scientific literacy requirement in those nations. Instituting such a requirement in all nations, and improving the quality and quantity of such courses on U.S. campuses, would increase global scientific literacy significantly, arguably doubling Europe's scientific literacy rate. In view of this result and today's crying need for scientific literacy, physics educators should make physics for nonscientists their top priority.
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01.40.Fk Research in physics education
01.75.+m Science and society

A Multipurpose Device for Some Hydrostatics Questions

Salvatore Ganci

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 407

Online Publication Date: Sep 2008

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A number of well-known hydrostatics problems dealing with Archimedes' principle concern a loaded boat floating in a pool.1–4 Examples of this sort of problem include: 1. (a) If a stone is thrown overboard from a boat floating in a pool, does the water level in the pool rise, fall, or remain unchanged? (b) If a hole is made in the bottom of the boat so that the boat sinks, does the water level in the pool change? If so, when does the change begin (when water first begins to enter the boat or later)? 2. A boat floating in a pool carries a mass M that can either be placed on the raft or hung below the raft. (a) How does the water level in the pool compare in the two cases? (b) In which case does the raft float higher in the water? This paper describes a simple low-cost experimental setup that can be used to demonstrate the solutions to such problems in a concrete and dramatic way.
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01.50.Pa Laboratory experiments and apparatus
01.50.My Demonstration experiments and apparatus
01.40.gb Teaching methods and strategies

How Does It Sound? Young Interferometry Using Sound Waves

Roberto Machorro and E. C. Samano

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 410 | Cited 1 time

Online Publication Date: Sep 2008

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This paper describes an enjoyable, simple, and inexpensive way to perform Young's two-source experiment using sound waves. The wave source is a simple aluminum rod (a “singing rod”).1–3
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01.50.Pa Laboratory experiments and apparatus
01.55.+b General physics

Computer-Based Experiment for Determining Planck's Constant Using LEDs

Feng Zhou and Todd Cloninger

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 413 | Cited 4 times

Online Publication Date: Sep 2008

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Visible light emitting diodes (LEDs) have been widely used as power indicators. However, after the power is switched off, it takes a while for the LED to go off. Many students were fascinated by this simple demonstration. In this paper, by making use of computer-based data acquisition and modeling, we show the voltage across the LED undergoing an exponential decay after the power is switched off. We also describe a new approach for determining Planck's constant using LEDs. The simple experiment can be used either in an interactive lecture demonstration or an entry-level physics lab.
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01.50.H- Computers in education
01.50.Pa Laboratory experiments and apparatus
01.40.gb Teaching methods and strategies

Einstein's Mirror

Aleksandar Gjurchinovski and Aleksandar Skeparovski

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 416

Online Publication Date: Sep 2008

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Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity.1–4 The problem was first investigated by Einstein in his famous 1905 paper by using the Lorentz transformations to switch from the mirror's rest frame to the frame where the mirror moves at a constant velocity.5 Einstein showed an intriguing fact that the usual law of reflection would not hold in the case of a uniformly moving mirror, that is, the angles of incidence and reflection of the light would not equal each other. Later on, it has been shown that the law of reflection at a moving mirror can be obtained in various alternative ways,6–10 but none of them seems suitable for bringing this interesting subject into the high school classroom.
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01.40.Fk Research in physics education
01.40.ek Secondary school
01.40.gb Teaching methods and strategies

Congratulations to the 2008 U.S. Physics Team

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 419

Online Publication Date: Sep 2008

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It takes a village … Many people worked hard to send the U.S. Physics Team to the 2008 International Physics Olympiad in Hanoi this summer — Who got them involved, got them trained, and got them to Vietnam and back?
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01.50.Rt Physics tournaments and contests
01.10.Cr Announcements, news, and awards

The Hybrid Automobile and the Atkinson Cycle

Bernard J. Feldman

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 420

Online Publication Date: Sep 2008

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The hybrid automobile is a strikingly new automobile technology with a number of new technological features that dramatically improve energy efficiency. This paper will briefly describe how hybrid automobiles work; what are these new technological features; why the Toyota Prius hybrid internal combustion engine operates on the Atkinson cycle instead of the Otto cycle; and what are the advantages and disadvantages of the hybrid automobile. This is a follow-up to my two previous papers on the physics of automobile engines.1,2
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01.50.-i Educational aids
01.75.+m Science and society
01.40.J- Teacher training

Gender Differences in the High School and Affective Experiences of Introductory College Physics Students

Zahra Hazari, Philip M. Sadler, and Robert H. Tai

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 423 | Cited 7 times

Online Publication Date: Sep 2008

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The disparity in persistence between males and females studying physics has been a topic of concern to physics educators for decades. Overall, while female students perform as well as or better than male students,1 they continue to lag considerably in terms of persistence. The most significant drop in females studying physics occurs between high school and college.2 Since most female physicists report that they became attracted to physics and decided to study it further while in high school, according to the International Study of Women in Physics,3 it is problematic that high school is also the stage at which females begin to opt out at much higher rates than males. Although half of the students taking one year of physics in high school are female, females are less likely than males to take a second or Advanced Placement (AP) physics course.4 In addition, the percentage of females taking the first physics course in college usually falls between 30% and 40%.1 In other words, although you may see gender parity in a first high school physics course, this parity does not usually persist to the next level of physics course. In addition, even if there is parity in a high school physics course, it does not mean that males and females experience the course in the same way. It is this difference in experience that may help to explain the drop in persistence of females.
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01.75.+m Science and society
01.40.Fk Research in physics education

A Time-of-Flight Method To Measure the Speed of Sound Using a Stereo Sound Card

Carlos C. Carvalho, J. M. B. Lopes dos Santos, and M. B. Marques

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 428 | Cited 3 times

Online Publication Date: Sep 2008

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Most homes in developed countries have a sophisticated data acquisition board, namely the PC sound board. Designed to be able to reproduce CD-quality stereo sound, it must have a sampling rate of at least 44 kHz and have very accurate timing between the two stereo channels. With a very simple adaptation of a pair of regular PC microphones, a computer with a stereo sound board, and sound analysis software, we were able to implement a method of accurate measurement of the speed of sound with several attractive features: a) The most expensive equipment, the PC, the sound board, and sound analysis software, are available in many homes and almost all schools; the two microphones and the additional electronics (see below) can be acquired for less than $50. b) The concept of the experiment is sufficiently simple to be grasped by very young students, 13–14 years old. c) The experiment itself is so straightforward that in a recent Open Day at our department, every group of students passing through the experiment was able to complete, in a couple of minutes, several measurements of cs, the speed of sound in air. d) It is possible to use the same apparatus to measure the speed of sound in solids.
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01.40.Fk Research in physics education
01.50.Pa Laboratory experiments and apparatus
01.55.+b General physics

Being Careful with PASCO's Kinetic Friction Experiment: Uncovering Pre-sliding Displacement?

T. M. Lawlor

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 432

Online Publication Date: Sep 2008

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The widely used PASCO laboratory equipment is an excellent way to introduce students to many topics in physics. In one case, PASCO's equipment may be too good! Various experiments exist for calculating the kinetic coefficient of friction by measuring the acceleration of a sliding object under some constant force. With ever more accurate equipment, such as electronic motion sensors, students are capable of measuring motion over quite small time intervals. In measuring motion including friction, PASCO equipment can record more complicated aspects of friction associated with the transition between static friction and kinetic friction. This serves as an excellent exercise to introduce some fine details of friction not typically discussed in an introductory physics course. In fact, if one does not consider these fine details (or at least does not omit them) the “canned” PASCO friction lab will yield wildly spurious results. The erroneous results obtained are due to a nonconstant “recoil” acceleration during the first ∼0.2 seconds of motion. The problem does not show up in the PASCO instructor's manual because the manual restricts the experiment to a small range of low applied forces for which the effect is minor. The recoil was actually observed previously1 but was written off as equipment noise. If one ignores this “noise,” a relatively constant coefficient of kinetic friction can be found in this lab experiment, as we will show. We describe here the original experiment, a second experiment to rule out that this is an experiment-specific phenomenon, and how the experiments can be used for two or three different topics. Finally, we tabulate results and discuss what may be causing this “recoil.”
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01.50.Pa Laboratory experiments and apparatus
01.40.gb Teaching methods and strategies
01.55.+b General physics
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A Toy “Magnetometer”

A. Cary, E. Mayfield, and J. Mottmann

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 437

Online Publication Date: Sep 2008

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Everyone likes to play with toys and entertain themselves with devices built to amuse or mystify. The authors became intrigued with tabletop devices originally designed to demonstrate magnetic “levitation.” Toys of this type can be purchased commercially1 or assembled from a kit.2 We found that such an inexpensive device could be used to monitor the daily variations in the Earth's local magnetic field. A comparison of our daily observations with those of international geomagnetic observatories shows remarkably similar patterns of magnetic variation.
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01.50.My Demonstration experiments and apparatus
01.50.Wg Physics of toys
85.70.-w Magnetic devices
93.00.00 Geophysical observations, instrumentation, and techniques
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The River Needs a Cork

Guy Vandegrift

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 440

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
01.40.Fk Research in physics education
01.55.+b General physics
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October Surprise

Boris Korsunsky

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 441

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.Rt Physics tournaments and contests
01.40.J- Teacher training
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Fermi Questions

Larry Weinstein

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 442

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.Rt Physics tournaments and contests
01.55.+b General physics
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Umbrella Coil

Norihiro Sugimoto (Stray Cats)

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 443

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
01.40.E- Science in school
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Journal Writing in the Physics Classroom

J. Johanna Hopp

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 445

Online Publication Date: Sep 2008

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J. Johanna (Jo) Hopp is an assistant professor of physics at the University of Wisconsin-Stout, where she teaches both a one-semester calculus-based introductory course and a conceptual-based course. She received her doctorate from the University of Washington Department of Physiology and Biophysics.
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01.40.Fk Research in physics education
01.40.J- Teacher training
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Measurement Uncertainty “Error Calculator:” http:∕∕physics.gac.edu∕%7Ehuber∕error%5Fcalc∕

Tom Huber

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 447

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.H- Computers in education
01.30.Xx Publications in electronic media

New Resources at the Astronomical Society of the Pacific Website

Andrew Fraknoi, Chair

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 447

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.H- Computers in education
01.40.J- Teacher training

New Physics and Astronomy songs online:

Jeffery Mondak and James M. Benson, Chair

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 447

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.H- Computers in education
01.50.F- Audio and visual aids

Understanding Exponential Growth and e: activities and videos

David Rheam, Math Teacher

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 447

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.50.H- Computers in education
01.50.F- Audio and visual aids
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How many …? How much …? Guesstimation: Solving the World's Problems on the Back of a Cocktail Napkin: Lawrence Weinstein and John A. Adams

John L. Hubisz

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 448

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.30.Vv Book reviews
01.40.gb Teaching methods and strategies

Microreviews by the Book Review Editor: Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions: Lisa Randall

John L. Hubisz

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 448

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.30.Vv Book reviews
01.30.Os Books of general interest to physics teachers

Microreviews by the Book Review Editor: Death by Black Hole and Other Cosmic Quandaries: Neil deGrasse Tyson

John L. Hubisz

The Physics Teacher -- October 2008 -- Volume 46, Issue 7, pp. 448

Online Publication Date: Sep 2008

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Abstract Unavailable
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01.30.Vv Book reviews
01.30.Os Books of general interest to physics teachers
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