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Science SPORE Prize
November 2011

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The Open Source Physics Project is supported by NSF DUE-0442581.

Folder Mario Belloni's Shared Folder

Folder Folder Summer 2011 AAPT Talk Resources
Summer 2011 AAPT Talk Resources  (9 resources)
This folder contains materials discussed in the Invited Talk at the Summer 2011 AAPT Meeting in Omaha, NE
Physlets and Physlet Physics Jar
The Physlets jar file contains forty (40) Java applets known as Physlets.  Applets are not stand-alone programs and must be embedded into html pages to be useful.   Physlet applets are small computational engines that are are designed to be scripted using JavaScipt.  See the Physlets and the Physlet Physics books for additional details.
Easy Java Simulations Modeling and Authoring Tool
Easy Java Simulations (EJS) is a Java program that enables both programmers and novices to quickly and easily prototype, test, and distribute packages of Java simulations.
Orbiting and Colliding Galaxies 3D Model
The Orbiting and Colliding Galaxies 3D Model is a three-dimensional extension of the Alar and Juri Toomres' 1972 supercomputer model of colliding galaxies.  This model assumes that galactic centers are point masses and the orbiting stars do not interact with each other (the galactic cores interact with each other and the individual stars). Unlike the Toomres' model (and the Colliding Galaxies model by Christian and Lim), both galactic cores begin with a compliment of stars orbiting their respective cores. These stars start in a 3-D circular orbit about the center of each galaxy in one plane. When the two galaxies pass each other they produce the long spiraling tails.
Phases of Moon Model
The EJS Phases of Moon model displays the appearance of Moon and how it changes depending on the position of Moon relative to Earth and Sun. The main window shows Earth (at the center) and Moon, as well as a circle tracing out Moon's orbit. Sun is far to the right in this picture  and therefore the right side of Earth and Moon are bright while the left sides are dark.  By using the Options Menu the Moon View window shows the appearance of Moon as seen from Earth  when Moon is in the position shown in the main window.  You can modify  this simulation if you have Ejs installed by right-clicking within the plot and selecting  "Open Ejs Model" from the pop-up menu item.
Sidereal and Solar Day
The Sidereal and Solar Day model illustrates the difference between the sidereal and solar day. The planets of our solar system both orbit around Sun and rotate on their axis. These two rotations allow for multiple definitions of what a day is.  This simulation shows the orbit and rotation of a planet (blue) around Sun (orange). It uses an orange arrow to represent where Sun would be seen in the sky relative to the background stars.  A point on the rotating planet is shown with a red arrow to indicate where that point faces relative to the background stars. In order to account for the true scale of the distance of the stars away from the planer, a longer red arrow from Sun points in the same direction as the arrow on the planet to indicate where this point faces relative to the background stars.  Users can toggle between the geocentric and heliocentric point of view. The parameters are initially set to model the orbit and rotation of Earth.
Exoplanet Detection: Transit Method
The Exoplanet Detection: Transit Method model simulates the detection of exoplanets by using the transit method. In this method, the light curve from a star, and how it changes over time due to exoplanet transits, is observed and then analyzed. In this simulation the exoplanet orbits the star (sun-sized) in circular motion via Kepler's third law.  When the exoplanet passes in front of the star (transits), it blocks part of the starlight. This decrease in starlight is shown on the graph.  If the exoplanet is close enough to the central star, and has sufficient reflectivity, or albedo, it can reflect enough of the starlight to be seen on the light curve. In the simulation the star-exoplanet system is shown as seen from Earth (edge on view) but magnified greatly, and with the star and planet sizes not shown to the scale of the orbit. The radius of the central star (relative to the radius of Sun),semi-major axis of the exoplanet (in AU), radius of the exoplanet (relative to the radius of Jupiter), the exoplanet's albedo (reflectivity), and the inclination of the system relative to Earth can be changed.
Swinging Atwood's Machine Model
The Swinging Atwood's Machine Model is an extension of the traditional Atwood's machine where one hanging mass is allowed to swing like a pendulum. One assumes that all motions for the swinging mass are possible including positions above the second peg which requires that the string remains rigid at all times. Unlike the traditional Atwood's machine, orbits or cycles are possible. In other words, for certain conditions, the motion of the Atwood's machine can continue indefinitely. In changing the ratio of the two masses and the initial angle of displacement, the trajectory of the swinging mass changes.  The object of this simulation is to model that system and allow the user a large amount of control over initial conditions so that they may fully explore the system.
Slash-Dot System Model
The Slash-Dot Model simulates a massive line segment and massive point rotating about one another due to gravity in a 2-dimensional plane. The simulation tracks the obits of the line segment (or "slash") and the point (or "dot") with colored trails. It also shows vectors of slash/dot velocity and acceleration and has a histogram depicting force. The white slash and dot are draggable. The orange velocity vectors are draggable: Simply click on the triangle of the arrow and drag around the plane. The longer the arrow gets, the greater the velocity of the slash or dot.
Solar Photon Random Walk
The Solar Photon Random Walk Model simulates the path of photons in radiative transport as they escape from the Sun. Photons do not travel in a straight line, but rather collide with larger particles and get redirected in a fashion. This simulation models that process using a random walk in polar coordinates. The step size for this random walk are determined by the mean free path, the average distance the photon will travel before colliding with another particle. This mean free path (l) is equal to the inverse of the product of the density (p) and the opacity (k): l = 1/(k*p). The density and opacity of the Sun are not constant throughout, but rather change at different distances from the center. However, these values are not agreed upon among the scientific communtiy. Using different values of the mean free path, physicists give the average escape time of photons anywhere from between 100,000 years and 1,000,000 years. As a result, the program was designed not only to take into account a few different physicists' values (both average and linearly decreasing values) but it also allows the user to input their own values.
The OSP Network:
Open Source Physics - Tracker - EJS Modeling
Physlet Physics
Physlet Quantum Physics