Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session D11: SPS Undergraduate Research II |
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Chair: Ann Viano, Rhodes College Room: Maryland C |
Saturday, February 13, 2010 1:30PM - 1:42PM |
D11.00001: Introductory Physics Experiments Using the Wii Balance Board Julian Starr, Robert Sobczak, Zohaib Iqbal, Romulo Ochoa The Wii, a video game console by Nintendo, utilizes several different controllers, such as the Wii remote (Wiimote) and the balance board, for game-playing. The balance board was introduced in early 2008. It contains four strain gauges and has Bluetooth connectivity at a relatively low price. Thanks to available open source code, such as GlovePie, any PC with Bluetooth capability can detect the information sent out by the balance board. Based on the ease with which the forces measured by each strain gauge can be obtained, we have designed several experiments for introductory physics courses that make use of this device. We present experiments to measure the forces generated when students lift their arms with and without added weights, distribution of forces on an extended object when weights are repositioned, and other normal forces cases. The results of our experiments are compared with those predicted by Newtonian mechanics. [Preview Abstract] |
Saturday, February 13, 2010 1:42PM - 1:54PM |
D11.00002: Galileo on Two Wheels: Why Does Newton Make Me Keep Pedaling This Thing? Dave Gardner, Kate Osenbach, Joseph Connolly As part of an effort to use examples for the bicycle to illustrate basic physics principles, we have been exploring the application of Newton's laws of motion to a moving bicycle. In particular, we have developed methods to measure the bicycle's two primary forces of resistance-tire rolling resistance and air resistance on rider and bike. With the use of minimal equipment such as stopwatches and bicycle speedometers, we have obtained data that provide a very good fit to simple models and closed differential equation solutions. We have also found that the bicycle affords a simple, low tech, and convenient method to study concepts of terminal velocity and rolling resistance. Just as Galileo made use of inclined planes to study falling objects, we used gently sloping hills to determine forces on the moving bicycle. Our methods make use of a novel technique to determine the bicycle and rider frontal cross sectional area. We hope our methods and results will be of interest to students of physics and mathematics and to the general cycling community. We have found it is possible for a cyclist to easily measure; without the use of expensive time in a wind tunnel; the effects of various body positions on wind resistance. This paper also examines the force and power consequences of riding at high speeds. [Preview Abstract] |
Saturday, February 13, 2010 1:54PM - 2:06PM |
D11.00003: Classical Mechanics Experiments using Wiimotes Alexander Lopez, Romulo Ochoa The Wii, a video game console, is a very popular device. Although computationally it is not a powerful machine by today's standards, to a physics educator the controllers are its most important components. The Wiimote (or remote) controller contains a three-axis accelerometer, an infrared detector, and Bluetooth connectivity at a relatively low price. Thanks to available open source code, such as GlovePie, any PC or Laptop with Bluetooth capability can detect the information sent out by the Wiimote. We present experiments that use two or three Wiimotes simultaneously to measure the variable accelerations in two mass systems interacting via springs. Normal modes are determined from the data obtained. Masses and spring constants are varied to analyze their impact on the accelerations of the systems. We present the results of our experiments and compare them with those predicted using Lagrangian mechanics. [Preview Abstract] |
Saturday, February 13, 2010 2:06PM - 2:18PM |
D11.00004: The Effects of Fluid Absorption on the Mechanical Properties of Joint Prostheses Components David Yarbrough, Ann Viano Ultra-high-molecular-weight polyethylene (UHMWPE) is the material playing the role of cartilage in human prosthetic joints. Wear debris from UHMWPE is a common reason for joint arthroplasty failure, and the exact mechanism responsible for wear remains an area of investigation. In this study, the microstructure of UHMWPE was examined as a function of fluid absorption. Samples with varying exposure to e-beam radiation (as part of the manufacturing process) were soaked for forty days in saline or artificial synovial fluid, under zero or 100 lbs load. Samples were then tensile-tested according to ASTM D-3895. The post-stressed material was then examined by transmission electron microscopy to evaluate the molecular response to stress, which correlates with macroscopic mechanical properties. Three parameters of the crystalline lamellae were measured: thickness, stacking ratio, and alignment to stress direction. Results indicate that fluid absorption does affect the mechanical properties of UHMWPE at both the microscopic and microscopic levels. [Preview Abstract] |
Saturday, February 13, 2010 2:18PM - 2:30PM |
D11.00005: Optical Tweezing of Yeast Cells Kyle Gilroy, Romulo Ochoa Optical Tweezers is a powerful technique that aids in understanding and applying the unique principles of photonics, optical physics, and basic cell biology. The experiments presented involve using HeNe lasers (632.8 nm) to trap spherical and ovular shaped objects in a solution. Polystyrene spheres, six micrometers in diameter, were trapped and moved with the laser to calibrate our system. The spheres were submerged in a Sodium Phosphate buffer solution to prevent sticking. Saccharomyces cerevisae, better known as yeast, was grown in a glucose rich environment to reach sizes of four to nine micrometers. Our optical tweezers captured and moved these cells under the operators command. A two laser system was utilized to control two cells simultaneously and attempt the splitting of cells. [Preview Abstract] |
Saturday, February 13, 2010 2:30PM - 2:42PM |
D11.00006: Raman Spectroscopy of Cocrystals Frank Rooney, Paul Reardon, Romulo Ochoa, Heba Abourahma, Marcus Marti, Rachel DiMeo Cocrystals are a class of compounds that consist of two or more molecules that are held together by hydrogen bonding. Pharmaceutical cocrystals are those that contain an active pharmaceutical ingredient (API) as one of the components. Pharmaceutical cocrystals are of particular interest and have gained a lot of attention in recent years because they offer the ability to modify the physical properties of the API, like solubility and bioavailability, without altering the chemical structure of the API. The APIs that we targeted for our studies are theophylline (Tp) and indomethacin (Ind). These compounds have been mixed with complementary coformers (cocrystal former) that include acetamide (AcONH2), melamine (MLM), nicotinic acid (Nic-COOH), 4-cyanopyridine (4-CNPy) and 4-aminopyridine (4-NH2Py). Raman spectroscopy has been used to characterize these cocrystals. Spectra of the cocrystals were compared to those of the coformers to analyze for peak shifts, specifically those corresponding to hydrogen bonding. A 0.5 m CCD Spex spectrometer was used, in a micro-Raman setup, for spectral analysis. An Argon ion Coherent laser at 514.5 nm was used as the excitation source. [Preview Abstract] |
Saturday, February 13, 2010 2:42PM - 2:54PM |
D11.00007: Comparison of Sprite-Halo Characteristics Imaged Over the USA and South America Lance Petersen, Mike Taylor, Dominique Pautet, Matthew Bailey, Steve Cummer Sprites and Halos are prominent members of an extraordinary family of Transient Luminous Events (TLEs) that have been discovered over the past 20 years. Halos are short-lived (few millisecond) diffuse optical emissions that appear as horizontal bright disks suspended above distant thunderstorms. They frequently precede the formation of a vertically structured sprite. Reports of halos are relatively few and indicate a limited height range centered at approximately 80 km with optical diameters up to about 100 km. Unlike sprite events, which occur almost exclusively in association with large positive cloud-to-ground lightning discharges, halos have recently been observed from satellites in association with both positive and negative discharges. This presentation compares the optical and electrical properties of a large number of halos and sprite-halos imaged over the U.S. Great Plains and over Northern Argentina in South America. Our goal is to improve current knowledge of their characteristics and variability. [Preview Abstract] |
Saturday, February 13, 2010 2:54PM - 3:06PM |
D11.00008: Examination of wave band pattern feature observed in northwestern Monterey Bay airborne imagery during the 2009 SARP project Iva Gerasimenko, Kamil Armaiz-Nolla, Michael Glotter On July 22, 2009, MASTER data was obtained from the DC-8 flying laboratory over the Monterey Bay region, and an unusual banded wave structure was observed in the northwest corner of the bay, approximately half a kilometer off-shore. This structure consisted of alternating dark and light bands, each 350 meters wide and 1500 meters long. Three possible explanations for the nature of the phenomenon were proposed: Langmuir cells, internal waves, or the small scale atmospheric-ocean interaction in the form of wind jets and supercritical airflow. ENVI, Excel, MATLAB and Google Earth programs were used to analyze the data. Results of this analysis were then examined in light of each of the three theories, in order to determine which explanation is more or less likely. The effect of the feature on the biological and chemical make-up of the immediately adjacent area was also studied through the in-situ data of the ocean surface layer collected by boat in Monterey Bay. If the bands observed alter physical conditions in some way that could affect the biology of the area, it is important to understand the nature of those bands and to see whether or not their presence introduces any significant change. [Preview Abstract] |
Saturday, February 13, 2010 3:06PM - 3:18PM |
D11.00009: Astronomical Dating of Edvard Munch's Summer Sky Paintings Ava Pope, Donald Olson Norwegian painter Edvard Munch, most famous for \textit{The} \textit{Scream,} created many spectacular works depicting the skies of Norway. Our Texas State group used astronomical methods to analyze three of these paintings: \textit{Starry Night}, \textit{The Storm,} and \textit{Sunrise in Asgardstrand}. Astronomical dating of these paintings has some importance because the precise days when Munch visited Asgardstrand are unknown. Our research group traveled to Norway in August 2008 to find the locations from which Munch painted these three works. We then used astronomical calculations, topographical analysis, historical photographs, and weather records to determine the precise dates and times for the scenes depicted in these paintings. [Preview Abstract] |
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