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Oct 2011

Volume 49, Issue 7, pp. 404-463

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Physics and pizza circles

Terrence P. Toepker

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 404

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
01.40.-d Education

Comments on “Dramatic (and Simple!) Demonstration of Newton's Third Law”

C. K. Lee and H. K. Wong

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 404

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
01.50.My Demonstration experiments and apparatus

More meanings of “=” in AP® Physics

Wang Xiaoyu

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 405

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Abstract Unavailable
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99.10.Np Editorial note
01.50.-i Educational aids

Correction to “Effective Torsion and Spring Constants in a Hybrid Translational-Rotational Oscillator” Phys. Teach. 49, 106–109 (Feb. 2011)

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 405

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99.10.Jk Corrected article
84.30.Ng Oscillators, pulse generators, and function generators
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Klopsteg Memorial Lecture Award

David Cook, Past President

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 406

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01.10.Cr Announcements, news, and awards
01.40.-d Education
92.60.Ry Climatology, climate change and variability

Robert A. Millikan Medal

David Cook, Past President

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 406

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Abstract Unavailable
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01.10.Cr Announcements, news, and awards

Distinguished Service Citations

David Cook, Past President

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 406

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01.10.Cr Announcements, news, and awards
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FALLING BALLS

Paul Hewitt

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 408

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
47.00.00 Fluid dynamics
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Launch of a Vehicle from a Ramp

Rod Cross

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 410

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Avehicle proceeding up an inclined ramp will become airborne if the ramp comes to a sudden end and if the vehicle fails to stop before it reaches the end of the ramp. A vehicle may also become airborne if it passes over the top of a hill at sufficient speed. In both cases, the vehicle becomes airborne if the point of support underneath the vehicle falls below the trajectory that would be followed by the vehicle in the presence of gravity alone. When the vehicle becomes airborne, the normal reaction force exerted by the ramp or the hill drops to zero, first on the front wheels and then on the rear wheels. Just prior to the vehicle's becoming airborne, the normal reaction force on the rear wheels acts to exert a torque on the vehicle, causing the vehicle to rotate. After the rear wheels become airborne, the vehicle will continue to rotate until it lands some distance from the launch point.
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01.50.My Demonstration experiments and apparatus
45.40.Gj Ballistics (projectiles; rockets)
89.40.Bb Land transportation
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The Joy of Teaching and Writing Conceptual Physics

Paul G. Hewitt

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 412 | Cited 2 times

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When I began teaching at City College of San Francisco in 1964, I fell in love with a 1960 text-book that addressed non-science students, Physics for the Inquiring Mind, written by British-born physicist Eric M. Rogers, who taught physics at Princeton University and who later won the 1969 Oersted Medal of the American Association of Physics Teachers. His book was as inspirational as he was and remains a favorite of mine. My request to adopt that book for my physics class was rejected by my department chair, Art Austin, who claimed it was much too bulky and heavy for students to have to haul around. It weighed more than five pounds, with a trim size huge for that time—8 × 11 inches. To further justify its rejection, he also found topics considered important not covered in the book. I would have loved teaching from the Rogers book, but such was not to be.
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01.40.gb Teaching methods and strategies
01.30.Os Books of general interest to physics teachers
01.20.+x Communication forms and techniques (written, oral, electronic, etc.)

Preparing Your Students for Careers in Science and Engineering: How Is Your State Doing?

Susan White and Paul Cottle

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 418

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With one glance at the starting salaries of new bachelor's degree recipients in Fig. 1, a teacher or parent can see the career fields to which their high school students interested in the best economic opportunities might aspire: several engineering fields (chemical, electrical, mechanical), computer science, physics, and mathematics.
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01.40.ek Secondary school

Decay Times and Quality Factors for a Resonance Apparatus

Heather Stephens, Austin Tam, and Michael Moloney

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 421

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The commercial resonance demonstration apparatus1 shown in Fig. 1 exhibits curious behavior. It consists of three pairs of slender spring-steel rods attached to a horizontal bar. When one of the rods is pulled aside and released, the rod of corresponding length is excited into visible motion, but the other rods remain apparently stationary. This may seem surprising because there is no noticeable motion of the bar or the base. The effect is achieved because each length of rod has its own frequency, and all of the rods are very lightly damped. A very lightly damped rod responds quite strongly when excited at its resonant frequency but barely responds at other frequencies (Fig. 2).
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01.50.My Demonstration experiments and apparatus
42.50.Wk Mechanical effects of light on material media, microstructures and particles
07.20.Pe Heat engines; heat pumps; heat pipes

The St. Louis Motor

Thomas B. Greenslade, Jr.

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 424

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The St. Louis Motor, invented in 1909, is unique among physics apparatus for being named for a geographical place rather than a physicist. The sturdy little device (Fig. 1) has never been out of production. Any older school or physics department that has not done a catastrophic housecleaning in the last 20 years will certainly have a small flock of them in the back room.
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01.50.My Demonstration experiments and apparatus
84.32.Hh Inductors and coils; wiring
84.50.+d Electric motors

Don't Erase that Whiteboard! Archiving Student Work on a Photo-Sharing Website

Edward Price, Stephen Tsui, Alicia Hart, and Lydia Saucedo

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 426

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Students in physics courses often use whiteboards to brainstorm, solve problems, and present results to the rest of the class, particularly in courses involving collaborative small group work and whole class discussions. The whiteboards contain a valuable record of students' collaborative work. Once a whiteboard is erased, however, its contents are lost and no longer accessible to students, instructors, or researchers and curriculum developers. We solve this problem using wireless-enabled digital cameras to create an archive of students' work on the photo-sharing website Flickr.com. This provides a persistent record of class activities that our students use frequently and find valuable. In this paper, we describe how this works in class and how students use the photos.
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01.50.ht Instructional computer use
07.68.+m Photography, photographic instruments; xerography

The Physics of “String Passing Through Ice”

Pirooz Mohazzabi

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 429

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One of the oldest yet interesting experiments related to heat and thermodynamics is placing a string on a block of ice and hanging two masses from the ends of the string. Sometime later, it is discovered that the string has passed through the ice without cutting it in half. A simple explanation of this effect is that the pressure caused by the string makes the ice melt just below the string, the string slides down, and the water freezes again just above the string.1–6 This phenomenon, however, is interesting and puzzling enough for many curious science students that it deserves a more detailed and quantitative explanation.
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01.50.Pa Laboratory experiments and apparatus
64.70.dj Melting of specific substances
65.40.G- Other thermodynamical quantities
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Projectile Motion Gets the Hose

John Eric Goff and Chinthaka Liyanage

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 432

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Students take a weekly quiz in our introductory physics course. During the week in which material focused on projectile motion, we not-so-subtly suggested what problem the students would see on the quiz. The quiz problem was an almost exact replica of a homework problem1 we worked through in the class preceding the quiz. The goal of the problem is to find the launch speed if the final horizontal and vertical positions and launch angle are given. Figure 1 shows a schematic of the trajectory.
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01.40.gb Teaching methods and strategies
01.50.Pa Laboratory experiments and apparatus
47.55.db Drop and bubble formation
45.40.Gj Ballistics (projectiles; rockets)
01.40.ek Secondary school

Teaching Quantum Uncertainty1

Art Hobson

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 434 | Cited 1 time

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An earlier paper2 introduces quantum physics by means of four experiments: Youngs double-slit interference experiment using (1) a light beam, (2) a low-intensity light beam with time-lapse photography, (3) an electron beam, and (4) a low-intensity electron beam with time-lapse photography. It's ironic that, although these experiments demonstrate most of the quantum fundamentals, conventional pedagogy stresses their difficult and paradoxical nature. These paradoxes (i.e., logical contradictions) vanish, and understanding becomes simpler, if one takes seriously the fact that quantum mechanics is the nonrelativistic limit of our most accurate physical theory, namely quantum field theory, and treats the Schroedinger wave function, as well as the electromagnetic field, as quantized fields.2 Both the Schroedinger field, or “matter field,” and the EM field are made of “quanta”—spatially extended but energetically discrete chunks or bundles of energy. Each quantum comes nonlocally from the entire space-filling field and interacts with macroscopic systems such as the viewing screen by collapsing into an atom instantaneously and randomly in accordance with the probability amplitude specified by the field. Thus, uncertainty and nonlocality are inherent in quantum physics. This paper is about quantum uncertainty. A planned later paper will take up quantum nonlocality.
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01.50.-i Educational aids
03.65.-w Quantum mechanics
01.40.Di Course design and evaluation

An Estimation of the Number and Size of Atoms in a Printed Period

Beth Schaefer, Edward Collett, Anne Tabor-Morris, and Joseph Croman

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 438 | Cited 1 time

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Elementary school students learn that atoms are very, very small. Students are also taught that atoms (and molecules) are the fundamental constituents of the material world. Numerical values of their size are often given, but, nevertheless, it is difficult to imagine their size relative to one's everyday surroundings. In order for students to obtain a quantitative understanding of the size of atoms, we have considered this problem by asking the following question: namely, how many atoms are in a printed period (.)? In this paper the number of atoms in a period is determined, along with a discussion and an equation to determine the radius of an atom. A related discussion regarding the size of atoms can be found in Ref. 1.
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01.40.eg Elementary school
01.50.-i Educational aids
30.00.00 ATOMIC AND MOLECULAR PHYSICS

Introducing Rotational Motion with EXIF Data

James Peterson

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 440

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In their article “Measuring the Flight Speed of Fire Bombers from Photos: An In-Class Exercise in Introductory Kinematics,” Greg W. Lowe and Eric Ayars1 remind us that photographs have always had physics hidden in them if you look hard enough. Since digital photos are embedded with EXIF data, vastly more physics can be explored with them. EXIF stands for “exchangeable image file format” and is data that are recorded into a photo when it is taken with a digital camera. Table I shows various methods for finding the EXIF data of a photo. I use one piece of this data to begin my unit on rotational motion.
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01.50.F- Audio and visual aids
07.68.+m Photography, photographic instruments; xerography
45.40.Bb Rotational kinematics

A School Experiment in Kinematics: Shooting from a Ballistic Cart

T. Kranjc and N. Razpet

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 442

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Many physics textbooks start with kinematics. In the lab, students observe the motions, describe and make predictions, and get acquainted with basic kinematics quantities and their meaning. Then they can perform calculations and compare the results with experimental findings. In this paper we describe an experiment that is not often done, but is interesting and attractive to students—the ballistic cart,1 i.e., the shooting of a ball from a cart moving along a slope. For that, one has to be familiar with one-dimensional uniform motion and one-dimensional motion with constant acceleration, as well as curvilinear motion that is a combination of such motions.1,2 The experimental results confirm theoretical predictions.
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01.50.Pa Laboratory experiments and apparatus
45.40.Gj Ballistics (projectiles; rockets)

A New Perspective on Eratosthenes' Measurement of the Earth

Ronald A. Brown and Alok Kumar

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 445

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Around 240 B.C., Eratosthenes made what is considered to be the most famous and accurate of the ancient measurements of the circumference of the Earth.1 It was accomplished by making presumably simultaneous measurements of the angles of the shadows cast by a vertical stick at Syene (today known as Aswan) and another at Alexandria, at noon on the day of the summer solstice (about June 21 every year). From these measurements, and knowing the distance from Syene to Alexandria along the assumed same meridian of longitude, Eratosthenes was able to provide a remarkably accurate estimate of the radius of the Earth.
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01.50.-i Educational aids
91.10.Jf Topography; geometric observations
01.30.Rr Surveys and tutorial papers; resource letters

Physics Myth Busting: A Lab-Centered Course for Non-Science Students

Martin John Madsen

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 448

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There is ongoing interest in how and what we teach in physics courses for non-science students, so-called “physics for poets” courses. Art Hobson has effectively argued that teaching science literacy should be a key ingredient in these courses.1 Hobson uses Jon Millers definition of science literacy, which has two components: first, “a basic knowledge of key scientific concepts,” and second, “an understanding of the process of science.”2 In preparing to teach our course for non-science students, I found that the majority of textbooks and courses focus on the first component. However, I wanted a lab-centered course that would give students hands-on practice doing science. I describe in this article a course I designed and implemented at Wabash College that focused on teaching students “the process of science.” The course was titled “Adventures in Physics: Mythbusters” and was based loosely on the popular Discovery Channel show “MythBusters.”3
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01.50.Qb Laboratory course design, organization, and evaluation
01.40.gb Teaching methods and strategies
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A do-it-yourself optical bench

Leoš Dvořák

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 452

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When teaching geometrical optics, especially the parts concerning lenses, there are many experiments that can be done just by holding the lenses in your (or your pupils') hands. But if you want to measure something, for example focal lengths, or combine two lenses to demonstrate the principle of a telescope, then something that can fix the lenses is needed. Of course, we can do such demonstrations and measurements using a commercially available optical bench. But a classical optical bench is usually a large and heavy construction that is not easy to transport. Often only one (or even none) may be available per classroom. In many school experiments something less robust, simpler, and less expensive would perhaps suit the needs better. Here we describe a simple and flexible optical bench that may be constructed by students themselves. Apart from the price of the lenses, the construction is also very cheap. So, if you have some spare lenses available, you can build a small optical bench for $10 or less. Each group of students can then use their own optical bench to do experiments.
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01.50.My Demonstration experiments and apparatus
01.50.Pa Laboratory experiments and apparatus
01.40.J- Teacher training
42.79.Bh Lenses, prisms and mirrors
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Physics Offerings Differ by Socioeconomic Profile of the School

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 455

Online Publication Date: Sep 2011

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When we look at physics offerings by socioeconomic profile of the school, we do not find dramatic differences in the number of seniors enrolled at each type of school; the number of physics teachers is also fairly evenly distributed. About one-third of the seniors and one-third of the physics teachers are at each type of school. However, there are significant differences in the number of physics classes and physics students by socioeconomic profile of the school. The nature of these differences means that teachers who teach physics at better-off schools are able to specialize in physics more easily, while those who teach at worse-off schools likely teach more classes in subjects outside physics.
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01.40.gb Teaching methods and strategies
01.75.+m Science and society
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Simple experimental setup to consolidate the angular momentum concept

M. Boutinguiza and F. Lusquiños

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 456

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
45.20.df Momentum conservation
01.50.ff Films; electronic video devices
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Putting it together

Diane Riendeau, Column Editor

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 457

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Abstract Unavailable
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01.50.fd Audio devices
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Cart before the horse

Boris Korsunsky, Column Editor

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 458

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Abstract Unavailable
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01.50.-i Educational aids
46.55.+d Tribology and mechanical contacts
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Fermi Questions

Larry Weinstein, Column Editor

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 458

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Abstract Unavailable
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01.50.-i Educational aids
92.10.Rw Sea ice (mechanics and air/sea/ice exchange processes)
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Physics Teacher Camp

John Burk and Josh Gates

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 459

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Imagine that you've just graduated law school. You've studied hard for years; you're highly trained and very knowledgeable. What you lack is experience. No matter—you jump right in and try hundreds of cases, doing your best and putting in hours above and beyond the usual work day. But suppose you don't have the support and resources of a law firm. You're doing it alone.
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01.40.gb Teaching methods and strategies
01.50.ht Instructional computer use
01.50.hv Computer software and software reviews
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“Can You See Me Now?” Using a favorite haunted physics laboratory project to teach color theory

Nancy Donaldson

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 460

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##
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01.50.My Demonstration experiments and apparatus
42.66.Ne Color vision: color detection, adaptation, and discrimination
42.79.Ci Filters, zone plates, and polarizers
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Al's relativistic adventures, by Kiran Sachdev, Jackie English and Bogdan Luca of the Perimeter Institute; http://www.onestick.com/relativity/

Dan MacIsaac, Column Editor

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 462

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Abstract Unavailable
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01.50.fh Posters, cartoons, art, etc.
03.30.+p Special relativity

How to get the most out of studying: Five 6 minute videos by Stephen Chew; http://www.youtube.com/playlist?list=PL85708E6EA236E3DB

Bill Goffe

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 462

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Abstract Unavailable
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01.50.ff Films; electronic video devices

30 lectures by distinguished astronomers describe the latest research in everyday language at the Astronomical Society of the Pacific, http://www.astrosociety.org/education/podcast/

Andrew Fraknoi

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 462

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Abstract Unavailable
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01.50.F- Audio and visual aids
01.50.hv Computer software and software reviews

Learning about science and religion (LASAR) from the Faraday Institute for Science and Religion; http://faradayschools.com/

Keith S. Taber

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 462

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Abstract Unavailable
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01.50.hv Computer software and software reviews
01.40.ek Secondary school
89.20.Hh World Wide Web, Internet
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The Tiger and the Physicist: Insights into the Physics We Teach: Robert P. Bauman

John L. Hubisz, reviewer

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 463

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Abstract Unavailable
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01.50.-i Educational aids

MicroReviews by the Book Review Editor: The Manga Guide to Relativity: Hideo Nitta, Masafumi, and Keita

John L. Hubisz, Column Editor

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 463

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Abstract Unavailable
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01.30.Vv Book reviews
01.50.fh Posters, cartoons, art, etc.
03.30.+p Special relativity
04.20.-q Classical general relativity

MicroReviews by the Book Review Editor: Gold Medal Physics: The Science of Sports: John Eric Goff

John L. Hubisz, Column Editor

The Physics Teacher -- October 2011 -- Volume 49, Issue 7, pp. 463

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Abstract Unavailable
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01.30.Vv Book reviews
01.55.+b General physics
87.85.gj Movement and locomotion
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