New Open Source Physics collection resources

Equatorial Coordinates Model

Sat, 14 Nov 2009 18:05:30 EST

The Equatorial Coordinates model displays the position of a star in equatorial (Right Ascension/Declination --- RA/Dec) coordinates. The horizon is shown along with the four cardinal directions (N, E, S, and W). The Latitude slider changes the latitude of the observer which is shown by the change in the (teal) celestial pole relative to the northern horizon. The position of the star can be changed by using the Right Ascension and Declination sliders. Once these coordinates are selected, pressing the play button will put the star, celestial grid, and the equatorial coordinates in motion to simulate the 23 hour and 56 minute motion of stars in the night sky. Equatorial Coordinates model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_EquatorialCoordinates.jar file will run the program if Java is installed. 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.

Solar and Lunar Eclipse Model

Fri, 13 Nov 2009 11:12:13 EST

The Solar and Lunar Eclipse model simulates the occurrences of solar and lunar eclipses. Moon's orbital inclination of 5.145 degrees with respect to the ecliptic (the Earth-Sun orbital plane) is what is responsible for solar and lunar eclipses not occurring every month. This inclination and the motion of Moon and Earth are depicted (the size of Sun, Earth, and Moon and the size of Moon's orbit are not shown to scale). The illuminated sides of Earth and Moon and the regions of possible eclipses (in yellow and green) are also depicted. In the Ecliptic View, the motion of Sun and Moon across the sky (+/- 7 degrees from the ecliptic) are shown. Moon's phase is shown and solar and lunar eclipses can occur on the ecliptic when Earth, Sun, and Moon line up properly. The Solar and Lunar Eclipse model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_SolarLunarEclipse.jar file will run the program if Java is installed. 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.

Circular Well Model

Thu, 12 Nov 2009 19:38:55 EST

The Circular Well model displays the 2D energy eigenstates of a particle trapped in a very deep two-dimensional circular well. Because the Schrödinger equation for this system is separable into radial and angular differential equations, the solution can be expressed as a product of a Bessel function and and a complex exponential. The Circular Well model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_CircularWell.jar file will run the program if Java is installed. 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.

Rectangular Well Superposition Model

Tue, 10 Nov 2009 22:10:46 EST

The Rectangular Well Eigenstate Superposition model displays the time evolution of the position-space wave function in an infinite 2D rectangular well using a superposition of energy eigenfunctions Ψ_n,m(x,y) with energy eigenvalues E_n,m. This model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_Superposition2DRectangularWell.jar file will run the program if Java is installed. 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.

Rectangular Well Model

Tue, 10 Nov 2009 21:17:35 EST

The Rectangular Well model displays the 2D energy eigenstates of a particle trapped in a very deep two-dimensional rectangular well. Because the Schrödinger equation for this system is separable into one-dimensional infinite square well Hamiltonians, the solution can be expressed as a product of the two one-dimensional infinite square well solutions. This model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_RectangularWell.jar file will run the program if Java is installed. 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.

Electric Field and Potential Model

Fri, 06 Nov 2009 12:11:27 EST

The EJS Electric Field and Potential Model shows the electric field and potential for cylindrical and spherical symmetry. In both symmetries, there are co-centric charged surfaces where the outer surface is grounded. The model reports the force on a test charge (yellow) between the co-centric surfaces as well as the voltage. 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. The Electric Field and Potential model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_ElectricFieldPotential.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Optics Interference: Ripple Tank Program

Fri, 06 Nov 2009 12:05:59 EST

The Optics Interference program simulates a ripple tank by showing the intensity of waves produced by a point source. Adding multiple point sources creates easily observable interference patterns showing constructive and destructive interference. Users can add point sources, move them around and change their wavelength. The Optics Interference program uses the algorithm described in Section 9.8 of "An Introduction to Computer Simulatuon Methods" by H. Gould, J. Tobochnik, and W. Christian. Optics Inteference is distributed as a ready-to-run (compiled) Java archive. Double clicking the optics_interference.jar file will run the program if Java is installed.

Foucault Rod Model

Tue, 03 Nov 2009 15:09:57 EST

The Foucault Rod model displays the vibration of a circumnavigating rod. One end of the rod is firmly secured to a support. The free end of the rod has a weight attached, like the bob of a pendulum. The support of the rod is circumnavigating a central axis. The plane of swing of the Foucault rod is affected by the rotation in the same way as the Foucault pendulum is. The simulation shows simultaneously the motion with respect to the inertial coordinate system, and the motion as seen from a co-rotating point of view. For the co-rotating view there is a close-up view and an overview. You can examine and 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. The Foucault Rod model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_nl_teunissen_foucault_rod.jar file will run the program if Java is installed. Additional information about this model can be found by visiting the author’s web site: http://www.cleonis.nl/index.htm.

Ballistics and Orbits Model

Tue, 03 Nov 2009 14:52:41 EST

The EJS Ballistics and Orbits model displays ballistic trajectories near the Earth. The model shows the trajectory with respect to the inertial coordinate system and the trajectory as seen from a point of view that is co-rotating with the Earth. You can examine and 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. The Ballistics and Orbits model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_nl_teunissen_ballistics_and_orbits.jar file will run the program if Java is installed. Additional information about this model can be found by visiting the author’s web site: http://www.cleonis.nl/index.htm.

Angular acceleration of a Contracting System Model

Tue, 03 Nov 2009 14:32:32 EST

The EJS Angular Acceleration of a Contracting System model shows a mass and pulley system to illustrate what happens when a rotating system contracts. When the centripetal force has contracted a rotating system to half its initial radius then: (1) The tangential velocity has doubled, (2) The angular velocity is 4 times faster, (3) The rotational kinetic energy is 4 times higher. (4) The required centripetal force is 8 times stronger. You can examine and 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. The Angular Acceleration of a Contracting System model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_nl_teunissen_angular_acceleration.jar file will run the program if Java is installed. Additional information about this model can be found by visiting the author’s web site: http://www.cleonis.nl/index.htm.

RLC Circuit Model

Mon, 05 Oct 2009 16:37:48 EST

The RLC Circuit model simulates a resistor, capacitor and inductor in series with either a sinusoidal or square wave voltage source and plots the time dependence of the voltage drops across each element. Users can vary the resistance, capacitance, inductance and source frequency. If Ejs is installed, right-clicking within the plot and selecting “Open Ejs Model” from the pop-up menu item allows for editing of the model. The RLC Circuit model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_RlcCircuit.jar file will run the program if Java is installed.

RC Circuit Model

Mon, 05 Oct 2009 16:37:18 EST

RC Circuit models the dynamical behavior of a voltage source attached in series to a resistor and capacitor. The source voltage can be chosen to be either a 10 volt sinusoidal or square wave with an adjustable frequency. Users can examine and change the model if they have Ejs installed. The RC Circuit model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_RcCircuit.jar file will run the program if Java is installed.

Faraday Disk Dynamo Model

Mon, 28 Sep 2009 07:42:51 EST

The EJS Faraday Disk Dynamo shows a conducting disk that rotates in a magnetic field. This produces a current (homopolar generator) and for certain configurations, it is a self-exciting dynamo. A self-exciting dynamo is the mechanical analog of a proposed mechanism to produce the earth and sun's magnetic fields. 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. The Faraday Disk Dynamo model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_FaradayDiskDynamo.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Falling Loop Model

Thu, 24 Sep 2009 13:45:46 EST

The EJS Falling Loop Model shows a conducting loop falling out of a region of uniform magnetic field. It plots the velocity of the loop as a function of time. Users can change the size and orientation of the loop as well as the extent and location of the uniform field. If Ejs is installed, right-clicking within the plot and selecting “Open Ejs Model” from the pop-up menu item allows for editing of the model. The Falling Loop model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_FallingLoop.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

MPTL 14 Workshop: Introduction to the OSP Collection

Thu, 24 Sep 2009 01:17:13 EST

These are the workshop notes for a basic introduction to the OSP collection and ComPADRE. The focus is on the use of the Filing Cabinet.

Electric Generator Model

Tue, 22 Sep 2009 14:05:02 EST

The EJS Electric Generator Model shows a simple electric generator made from a conducting loop rotating in a uniform magnetic field and connected to an ammeter. The model shows a plot of the magnetic flux and induced current. If Ejs is installed, right-clicking within the plot and selecting “Open Ejs Model” from the pop-up menu item allows for editing of the model. The Electric Generator model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_Generator.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Rail Gun Model

Fri, 18 Sep 2009 17:03:10 EST

The EJS Rail Gun Model simulates a rail gun created by running current through long rods generating a magnetic field that accelerates a current-carrying cross-rod. The simulation shows the generated magnetic field. Users can adjust the current in the rails and rod as well as the spacing between the rails. 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. The Rail Gun model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_RailGun.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Magnetic Bar Field Model

Fri, 18 Sep 2009 16:44:39 EST

The EJS Magnetic Bar Field Model shows the field of a bar magnet and has a movable compass that reports the magnetic field values. The bar magnet model is built by placing a group of magnetic dipoles along the bar magnet. 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. The Magnetic Bar Field model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_MagneticBarField.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Integer Programming Model for the Sudoku Problem

Sat, 12 Sep 2009 08:27:57 EST

The "Integer Programming Model for the Sudoku Problem" article in the The Journal of Online Mathematics and Its Applications uses an EJS binary integer linear model to solve this feasibility problem. Further, such an approach is extended to variations on the traditional Sudoku puzzle. In addition, we speculate as to how Sudoku puzzles are created, and provide several theorems for generating many new puzzles from one given original puzzle. EJS models allow for exploration with a variety of the ideas. Readers with Matlab and its Optimization Toolbox can solve Sudoku puzzles directly from an applet. Exercises and challenge problems that use principles from optimization, combinatorics, linear algebra, and computer science are presented for students.

Mountains of Fractals

Fri, 11 Sep 2009 14:22:39 EST

The "Mountauns of Fractals" article in the Math DL develops algorithms to produce coastlines and mountains in two dimensions by adapting mathematical ideas related to the construction of such fractals as Koch's curve. EJS is used to create hand's on activities that allow a reader to create a coastline with a rubberband, six-sided die, and thumb tacks and to explore the algorithms and the influence of their associated parameters. After discussing 2D fractal mountains, this article extends the 2D algorithm to produce 3D mountains. Finally, mathematical issues in random number generation are discussed. More specifically, linear congruential generators are considered and shown to be suitable as a random number generator for the 3D fractal landscape algorithm. The use of fractal landscapes in movies is also discussed.