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Feb 2012

Volume 50, Issue 2, pp. 68-126

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Meet Your New President, Jill Marshall

Karen L. Johnston

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 68

Online Publication Date: Jan 2012

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01.50.-i Educational aids
01.60.+q Biographies, tributes, personal notes, and obituaries
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The Many Faces of AAPT

Jill Marshall, AAPT President

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 69

Online Publication Date: Jan 2012

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SHOCKING TALE

Paul Hewitt

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 70

Online Publication Date: Jan 2012

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01.50.Pa Laboratory experiments and apparatus
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Charge and Energy Stored in a Capacitor

Yaakov Kraftmakher

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 73

Online Publication Date: Jan 2012

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Using a data-acquisition system, the charge and energy stored in a capacitor are measured and displayed during the charging/discharging process. The experiment is usable as a laboratory work and/or a lecture demonstration.
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01.50.My Demonstration experiments and apparatus
84.60.-h Direct energy conversion and storage

About the International System of Units (SI) Part IV. Writing, Spelling, and Mathematics

Gordon J. Aubrecht, II, Anthony P. French, and Mario Iona

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 77

Online Publication Date: Jan 2012

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01.50.-i Educational aids
06.20.fa Units

Measuring the Effects of Lift and Drag on Projectile Motion

Rod Cross

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 80

Online Publication Date: Jan 2012

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The trajectory of a projectile through the air is affected both by gravity and by aerodynamic forces.1 The latter forces can conveniently be ignored in many situations, even when they are comparatively large. For example, if a 145-g, 74-mm diameter baseball is pitched at 40 ms−1 (89.5 mph), it experiences a drag force of about 1.5 N. The gravitational force on the ball 1.42 N. Nevertheless, the trajectory of a baseball pitched without spin is not strongly affected by the drag force. Because the ball is relatively heavy and the flight distance is relatively small (about 60 ft), the drag force reduces the ball speed by only about 10% by the time it reaches the batter. As a result, the time taken for the ball to reach the batter is only about 5% longer than in a vacuum, and the actual trajectory is also very similar.2
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01.50.My Demonstration experiments and apparatus

Collisions with Springs: A Useful Context for the Study of Analytical Dynamics

Patrick Twomey, Colm O'Sullivan, John O'Riordan, and Stephen Fahy

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 83

Online Publication Date: Jan 2012

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A recent paper1 in this journal describes an experimental demonstration of the conservation of total momentum before, during, and after an elastic collision between two bodies. The experiment also appears to show that total kinetic energy is conserved in the process, including during the collision. There is a danger that this may give rise to some misconception given that, in any collision that takes place over a finite time, some kinetic energy must transfer to potential energy—albeit temporarily in the case of an elastic collision. Indeed, when a collision is observed in the c.m. frame, all kinetic energy is lost momentarily. The sequence of simple experiments described below, which can be performed using standard equipment available in undergraduate laboratories, was developed so that undergraduate students could study a collision process in some detail. It was designed to enable students to gain insight into a range of important ideas in elementary analytical dynamics, including conservation of momentum, energy transfer in inelastic collisions, and coefficient of restitution. An extension of the experiment also gives insight into wave propagation in elastic media.
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01.50.Lc Laboratory computer use

Removing the Mystery of Entropy and Thermodynamics — Part II

Harvey S. Leff

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 87 | Cited 1 time

Online Publication Date: Jan 2012

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01.50.-i Educational aids
05.70.Ce Thermodynamic functions and equations of state

Female representation by type of class

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 90

Online Publication Date: Jan 2012

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Last month we saw that females make up about 47% of all high school physics students in the United States. This number has changed little since 1997. This month, we take a closer look at female representation by type of class. We last collected class-specific data in 1993; that year, 43% of all high school physics students were female. However, female representation varies by type of class. In both 1993 and 2009, conceptual physics courses had the highest proportion of female students, and AP Physics C had the lowest. The good news is that female representation exhibits growth in all types of classes. In fact, the jump from 27% of the AP Physics C students being female in 1993 to 32% in 2009 represents an almost 20% growth in female representation; this compares favorably to the 9.3% growth overall.
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01.50.-i Educational aids

How Einstein Discovered E0 = mc2

Eugene Hecht

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 91

Online Publication Date: Jan 2012

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This paper traces Einstein's discovery of “the equivalence of mass [m] and energy [E0].” He came to that splendid insight in 1905 while employed by the Bern Patent Office, at which time he was not an especially ardent reader of physics journals. How then did the young savant, working outside of academia in semi-isolation, realize that these two seemingly disparate concepts were actually “identical”? Until now little attention has been given to exploring the physics that guided his thinking in this remarkable endeavor. That work culminated (1907) in the equation E0 = mc2, where E0 is “rest energy” and m is “invariant mass.” Despite claims to the contrary, Einstein did not write this equation, or its ambiguous variant,1 E = mc2, in 1905. Furthermore, we will propose a compelling reason for his otherwise inexplicable caution. This paper is meant to help clarify the contemporary literature in the service of an informed pedagogy.
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01.50.-i Educational aids

Discovery Garden — Physics and Architecture Meet Outside to Talk

Anne Tabor-Morris, Timothy Briles, Kathleen Froriep, and Catherine McGuire

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 95

Online Publication Date: Jan 2012

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The purpose of Georgian Court University's “Discovery Garden” is to create an experience of the physical sciences for students, both science and non-science majors, in a place of serenity: an outdoor garden. Why a garden? Consider that the traditional laboratory experience for students is one of stark rooms ventilated with noisy hoods and endemic with lab coats and safety glasses, an alien environment that can be a source of anxiety for some students studying science, while the idea of a garden excites the imagination and conjures peace. The garden also serves as a reminder that ideas learned in the classroom apply to the everyday world. In addition, the garden is a model of informal learning, which can be especially interesting for pre-service teachers. Outlined here are some general suggestions for the design of a science garden, applicability of educational philosophy to full-body experiences, and activities suggested for students and future teachers in such a garden, as well as a mini-tour of our garden.
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01.50.My Demonstration experiments and apparatus
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Millikan's Oil-Drop Experiment: A Centennial Setup Revisited in Virtual World

Michel Gagnon

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 98

Online Publication Date: Jan 2012

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Early in the last century, Robert Millikan developed a precise method of determining the electric charge carried by oil droplets.1–3 Using a microscope and a small incandescent lamp, he observed the fall of charged droplets under the influence of an electric field inside a small observation chamber. In so doing, Millikan demonstrated the existence of a fundamental unit of electric charge, and established its quantization. Now renowned as one of the most famous experiments of 20th-century physics, Millikan's oil-drop experiment has been reproduced with more or less success in most, if not all, high school and university physics classes. This has encouraged many improvements of the apparatus, now making this experiment much more accurate and easier to realize for advanced students. However, the required apparatus remains rather expensive, and for introductory college or high school students the experiment is still quite difficult to conduct. As an alternative to the traditional setup, a realistic computer-based simulator to replicate the Millikan oil-drop experiment has been developed. Using this software, students are able to undertake a complete experiment, obtain an accurate set of results, and thus gain a better understanding of the original experiment and its historical importance.
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01.50.Pa Laboratory experiments and apparatus

Cappuccino and Specific Heat Versus Heat of Vaporization

Frits Hidden, Jorn Boomsma, Anton Schins, and Ed van den Berg

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 103

Online Publication Date: Jan 2012

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A cappuccino is prepared by adding about 50 mL frothing, foaming milk to a cup of espresso. Whole milk is best for foaming and the ideal milk temperature when adding it to the espresso is 65 °C. The espresso itself may be warmer than that. During the heating the milk should not burn, as that would spoil the taste. The best way is to heat the milk slowly while stirring to froth the milk and create foam. But modern cappuccino machines in restaurants do not have time for slow heating. Could we heat the milk by just adding hot water?
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01.50.Pa Laboratory experiments and apparatus
81.40.Gh Other heat and thermomechanical treatments
65.20.Jk Studies of thermodynamic properties of specific liquids

Modeling Physical Systems Using Vensim PLE Systems Dynamics Software

Stephen Widmark

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 105

Online Publication Date: Jan 2012

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Many physical systems are described by time-dependent differential equations or systems of such equations. This makes it difficult for students in an introductory physics class to solve many real-world problems since these students typically have little or no experience with this kind of mathematics. In my high school physics classes, I address this problem by having my students use a variety of software solutions to model physical systems described by differential equations. These include spreadsheets, applets, software my students themselves create, and systems dynamics software.1 For the latter, cost is often the main issue in choosing a solution for use in a public school and so I researched no-cost software. I found Sphinx SD,2OptiSim,3 Systems Dynamics,4 Simile (Trial Edition),5 and Vensim PLE.6 In evaluating each of these solutions, I looked for the fewest restrictions in the license for educational use, ease of use by students, power, and versatility. In my opinion, Vensim PLE best fulfills these criteria.7
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01.50.ht Instructional computer use
02.30.Hq Ordinary differential equations

A Better 2-D Mechanical Energy Conservation Experiment

Michael Paesler

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 109

Online Publication Date: Jan 2012

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A variety of simple classical mechanics energy conservation experiments are used in teaching laboratories. Typical one-dimensional (1-D) setups may involve falling balls or oscillating springs. Many of these can be quite satisfying in that students can confirm—within a few percent—that mechanical energy is conserved. Students generally have little trouble identifying discrepancies such as the loss of a few percent of the gravitational potential energy due to air friction encountered by a falling ball. Two-dimensional (2-D) systems can require more sophisticated analysis for higher level laboratories, but such systems often incorporate complicating components that can make the exercise academically incomplete and experimentally less accurate. The following describes a simple 2-D energy conservation experiment based on the popular “Newton's Cradle” toy that allows students to account for nearly all of the mechanical energy in the system in an academically complete analysis.
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01.50.Pa Laboratory experiments and apparatus
84.60.Ve Energy storage systems, including capacitor banks
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Inertial Navigation: A Bridge Between Kinematics and Calculus

Philip M. Sadler, Eliza N. Garfield, Alex Tremblay, and Daniel J. Sadler

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 112

Online Publication Date: Jan 2012

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Those who come to Cambridge soon learn that the fastest route between Harvard and MIT is by the subway. For many students, this short ride is a quick and easy way to link physics and calculus. A simple, homemade accelerometer provides all the instrumentation necessary to produce accurate graphs of acceleration, velocity, and displacement position on this subterranean route. Each graph, in turn, reveals a story of the train's trip: speeding up and braking, varying track conditions, top speed, and the distance between subway stops deep beneath Massachusetts Avenue.
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01.50.-i Educational aids
06.30.Gv Velocity, acceleration, and rotation
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Binder clip optics bench for Young's double-slit experiment

Dave Van Domelen

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 116

Online Publication Date: Jan 2012

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Young's double slit is one of the standard experiments in wave optics, but getting the equipment to run it can be pretty expensive, and unless you expect to run a large number of different optics labs, it may not be a worthwhile capital outlay. But with some ingenuity and office supplies, a lot of the “real” equipment can be replicated well enough to let introductory students perform the experiment.
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01.50.My Demonstration experiments and apparatus
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
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Fermi Questions

Larry Weinstein, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 117

Online Publication Date: Jan 2012

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Diffraction experiments with infrared remote controls

Jochen Kuhn and Patrik Vogt

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 118

Online Publication Date: Jan 2012

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In this paper we describe an experiment in which radiation emitted by an infrared remote control is passed through a diffraction grating. An image of the diffraction pattern is captured using a cell phone camera and then used to determine the wavelength of the radiation.1
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01.50.My Demonstration experiments and apparatus
42.79.Dj Gratings
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Youtube Physics

Diane Riendeau, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 120

Online Publication Date: Jan 2012

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Through the use of YouTube, we can show our students demos that we do not have the capability of doing in class. We can use these videos to inspire them and show them some of the cutting-edge discoveries in our field. We can also show them videos from around the world. Students need to realize that the physics community is global, not just national. They should learn to marvel in the discoveries made by physicists from all nations.
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01.50.ht Instructional computer use
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To swing a ball

Wojciech Dindorf

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 121

Online Publication Date: Jan 2012

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01.50.My Demonstration experiments and apparatus
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Speaking the same language in physics and math

Marci Harvey

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 122

Online Publication Date: Jan 2012

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“Hey, is that the same thing as a derivative from calculus?” “Isn't that a quadratic equation?” These are some of the math-related questions my physics students ask every year. Some students realize that determining velocity from a position-time graph is the same thing as taking the first derivative in calculus or they recognize a quadratic equation has a t2 term. Why can all students not make the connection between the two? I wonder if we, as teachers of two different subjects, are making this learning more difficult because we have different terminology for identical concepts. We have an opportunity to create a learning environment that offers multiple opportunities to improve student comprehension. Teachers can connect the concepts from various classes into a cohesive set of information that can be used for higher-level thinking and processing skills.
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01.50.ht Instructional computer use
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Softball in space

Boris Korsunsky, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 123

Online Publication Date: Jan 2012

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Measurement of refractive index of a liquid

Paul Gluck and Taha Massalha

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 124

Online Publication Date: Jan 2012

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01.50.My Demonstration experiments and apparatus
07.60.Hv Refractometers and reflectometers
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YouTube Minute Physics channel by Henry Reich youtube.com/user/minutephysics

Dan MacIsaac, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 125

Online Publication Date: Jan 2012

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01.50.ht Instructional computer use

The Physics of Bicycle Stability bicycle.tudelft.nl/stablebicycle

Anthony Lapinski and Chuck Britton

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 125

Online Publication Date: Jan 2012

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01.50.-i Educational aids

John Bell video on YouTube youtube.com/watch?v=V8CCfOD1iu8

Dan MacIsaac, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 125

Online Publication Date: Jan 2012

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01.50.ht Instructional computer use
01.50.F- Audio and visual aids
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For the Love of Physics: From the End of the Rainbow to the Edge of Time—A Journey Through the Wonders Of Physics: Walter Lewin with Warren Goldstein

A. Gavrin

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 126

Online Publication Date: Jan 2012

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01.50.ht Instructional computer use

MicroRewiews by the Book Review Editor: Edward Bouchet; The First African-American Doctorate: Ronald E. Mickens

John L. Hubisz, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 126

Online Publication Date: Jan 2012

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01.50.-i Educational aids
01.30.M- Textbooks
01.30.Vv Book reviews

MicroRewiews by the Book Review Editor: Suspended in Language: Niels Bohr's Life, Discoveries, and the Century He Shaped: Jim Ottaviani and Leland Purvis

John L. Hubisz, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 126

Online Publication Date: Jan 2012

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01.50.-i Educational aids
03.65.Ud Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.)
01.30.M- Textbooks
01.30.Vv Book reviews

MicroRewiews by the Book Review Editor: • Something Out of Nothing: Marie Curie and Radium: Carla Killough McClafferty

John L. Hubisz, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 126

Online Publication Date: Jan 2012

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01.50.-i Educational aids
01.60.+q Biographies, tributes, personal notes, and obituaries

MicroRewiews by the Book Review Editor: Life and Death of a Star: Astronomy Magazine

John L. Hubisz, Column Editor

The Physics Teacher -- February 2012 -- Volume 50, Issue 2, pp. 126

Online Publication Date: Jan 2012

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01.50.-i Educational aids
01.30.M- Textbooks
01.30.Vv Book reviews
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