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Gluck, Paul; Perkalskis, Benjamin
2009 The Physics Teacher
doi: 10.1119/1.3072452
Optical elements manipulate light waves. They may be used to focus the light or to change the phase, the polarization, the direction, or the intensity of light. Many of these functions are often demonstrated with microwaves, since the devices normally available in teaching laboratories produce wavelengths in the centimeter range and are therefore more tangible. The same can be said for sound waves for frequencies in the kHz range. This property is the clue for producing elements such as half-wave plates, zone plates, and lenses for sound waves, based on techniques that have been developed for microwaves. This is the subject of the present article. Readers might wish to build some of these devices, which would then help to impress on students the unity of wave phenomena.
2009 The Physics Teacher
doi: 10.1119/1.3072453
Digital computers use different kinds of memory, each of which is either volatile or nonvolatile. On most computers only the hard drive memory is nonvolatile, i.e., it retains all information stored on it when the power is off. When a computer is turned on, an operating system stored on the hard drive is loaded into the computer's memory cache and system memory. Cache and system memory are volatile, i.e., data in them are lost when the computer is powered down. A more ideal computer would have nonvolatile memory for both cache and system memory to allow for “instant-on” capabilities. Of course any such memory would have to be as fast and as durable as existing volatile devices to be considered an improvement over current systems.;
Claycomb, James R.; Zachary, Christopher; Tran, Quoc
2009 The Physics Teacher
doi: 10.1119/1.3072454
Rocket experiments demonstrating conservation of momentum will never fail to generate enthusiasm in undergraduate physics laboratories. In this paper, we describe tests on rockets from two vendors 1,2 that combine baking soda and vinegar for propulsion. The experiment compared two analytical approximations for the maximum rocket height to the experimentally measured rocket height. Baking soda and vinegar rockets present fewer safety concerns and require a smaller launch area than rapid combustion chemical rockets. Both kits were of nearly identical design, costing ∼$20. The rockets required roughly 30 minutes of assembly time consisting of mostly taping the soft plastic fuselage to the Styrofoam nose cone.;
2009 The Physics Teacher
doi: 10.1119/1.3072455
In How to Solve It , accomplished mathematician and skilled communicator George Polya describes a four-step universal solving technique designed to help students develop mathematical problem-solving skills. By providing a glimpse at the grace with which experts solve problems, Polya provides definable methods that are not exclusive to mathematicians but of interest to cognitive psychologists and problem solvers in all fields. I had the good fortune to be introduced to Polya's ideas in my first undergraduate class in physics.;
Ilyes, Mark A.; Ortman-Link, Whitney
2009 The Physics Teacher
doi: 10.1119/1.3072456
Our school recently acquired 1 Vernier's Wireless Dynamics Sensor System (WDSS). The WDSS consists of a three-axis accelerometer, altimeter, and force sensor that has the ability to remotely collect data for later transfer to a computer.; 2 While our primary purpose for acquiring the WDSS was to enhance our amusement park physics experiments, we decided to test one of the WDSS units by using it to collect data during the drive home from school one day, since measuring the acceleration of a car is one of the experiments suggested in the Vernier Wireless Dynamics Sensor System User Manual. We taped the device to the floor of the car with its +; x -axis pointed forward and its +; y -axis pointed to the left. The WDSS was configured to take five samples per second for a total time period of 10 minutes.
2009 The Physics Teacher
doi: 10.1119/1.3072457
This little problem arose because I was frustrated with the standard electromagnetism texts, which show the magnetic field due to a current-bearing wire outside the wire ∝1/; r and inside ∝; r . However, they never point out that the moving electrons must be influenced by the magnetic field created by the other moving electrons. Clearly this must affect the solution. In this paper we will determine what that magnetic field does.
2009 The Physics Teacher
doi: 10.1119/1.3072458
In this paper I describe an in-class discussion activity aimed at helping elementary education majors in a physical science course think about issues surrounding the inclusion of “Intelligent Design” in public school science standards. I discuss the background instruction given, the content of the activity, and some results from its use in class.;
2009 The Physics Teacher
doi: 10.1119/1.3072459
Newton's law of gravitation is a central topic in the first-year physics curriculum. A lecturer can go beyond the physical details and use the history of gravitation to discuss the development of scientific ideas; unfortunately, the most recent chapter in this history, general relativity, is not covered in first-year courses. This paper discusses some topics that can be introduced with the judicious use of the dimensionless quantity ; GM/Rc; 2 ; deflection of light by a massive object, perihelion precession, gravitational redshifts, and the Global Positioning System (GPS).;
Allain, Rhett; Williams, Richard
2009 The Physics Teacher
doi: 10.1119/1.3072460
Suppose we had a brand new world to study—a world that possibly works with a different set of principles, a non-Newtonian world. Maybe this world is Newtonian, maybe it isn't. This world exists in video games, and it is open for exploration. Most video games try to incorporate realistic physics, but sometimes this does not happen. The obvious approach is to look at the source code for the game, but this would not allow students to apply analysis techniques.;
2009 The Physics Teacher
doi: 10.1119/1.3072461
Hot Wheels® Rev-Ups; 1 provide a pedagogically engaging and inexpensive culminating activity for the application of circular motion with constant speed in introductory mechanics. The introductory Rev-Up, shown in Fig. 1, consists of a very durable car with two strong magnets built into the front and back of the car. The track is a piece of flexible plastic with a built-in metallic strip through its center that can then be formed into a circle. Pushing the car forward several times on a flat surface allows the car to move in a vertical circle when placed inside the track. What makes this toy attractive is that the gearing system allows the car to move at a relatively constant speed for about three to five seconds before slowing down appreciably.
2009 The Physics Teacher
doi: 10.1119/1.3072466
Editor's note;; Luke Conlin taught high school physics in Massachusetts for five years. Currently he is working toward a PhD in Science Education at the University of Maryland, College Park, where he supervises intern teachers and conducts research on student reasoning.