Software Listing of Author : "Wolfgang Christian"
- Classical Helium Program
- License: Freeware
- Price: 0.00


The classical helium OSP program is a simple example of a three body problem and is similar to gravitational problem of a heavy sun and two light planets. The model consists of two electrons moving in a 2/r potential well and interacting through a 1/r potential. Initial conditions can be set to show phenomena such as autoionization or braided orbits. These conditions are stored in an xml document.
An EJS implementation of this model is also available. Search the OSP collection for classical helium.
Please note that this resource requires at least version 1.5 of Java.
written by Wolfgang Christian, Harvey Gould, and Jan Tobochnik
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 583 KB
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- Platform: WinOther
- Driven Mass and Spring Mesh Model for Windows
- License: Shareware
- Price:


The Driven Mass and Spring Mesh model displays the dynamics of a 2D array of masses coupled by springs and driven by a sinusoidal force. The model shows a time-dependent animation of the displacement or each mass.
The driving force can be applied at a single point (shown in red) or uniformly at all mesh points and the drive frequency f and amplitude A can be set as well as a damping coefficient b. As the frequency is varied the mesh vibrates strongly (resonates) at some frequencies and very little at others. These resonances have patterns that were first studied by Ernst Chladni and this simulation is designed to investigate these patterns using an idealized mass and spring model.
In order to find the resonances, it is useful to plot the mechanical energy as a function of frequency f after the system reaches its...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1126 KB
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- Platform: WinOther
- Falling U-Shaped Chain Model for Windows
- License: Freeware
- Price: 0.00


The Falling U-Shaped Chain model simulates the dynamics of a discrete falling chain with total length L and n links. Each link is acted on by the force of gravity mg and by the link-link interaction. A freely falling object is released near the last link for comparison. The surprise is that the acceleration of the last link can be larger than g.
Links in the model are assumed to be uniform rigid rods with mass m and length L/n connected by ideal joints. The first link is attached to a fixed point and the last link is releases a distance D from the fixed point. A small damping coefficient b is included to allow the chain to equilibrate to its hanging position below the fixed point.
The Falling U-Shaped Chain model was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1187 KB
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- Platform: WinOther
- Fermat Light Ray Model
- License: Freeware
- Price: 0.00


The Fermat Light Ray model shows a light ray traveling left to right through N homogeneous regions with different refractive indicies. Because light travels in a straight line through a homogenous medium, the path is determined by the vertical coordinates at each boundary. A data table allows users to set the region width w[i] and the refractive index n[i].
Fermat's principal states that the path taken by the light ray between the source and the detector is the path that requires the least time. The speed of light in each region is proportional to the refractive index in that region so the traversal time for region [i] is ?t=n[i]D where D is the ray-segment's length and we have chosen units such that the speed of light in vacuum c=1. The model begins with a straight path (light ray) connecting a source and a detector and...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 755 KB
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- Platform: WinOther
- Gyroscope Model
- License: Freeware
- Price: 0.00


The Gyroscope example computes and displays the dynamics of gyroscope under the influence of a gravitational torque acting on the center of mass. The gyroscope is supported at one end and given an initial angular velocity component about its axis of symmetry and a component perpendicular to its axis of symmetry. The numerical solution shows the motion for all initial conditions including zero initial angular momentum. The model is designed to show the cycloidal motion (precession and nutation) of the gyroscope axle when the initial angular velocity is large. Users can very the position and radius of the spinning mass as well as the initial angle and can display the angular momentum L, angular velocity ?, and torque N vectors. A second window shows the elevation angle of the axle and the angular momentum vector.
Units are...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1157 KB
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- Platform: WinOther
- Hard Disk PVT System Model for Windows
- License: Freeware
- Price: 0.00


The Hard Disk PVT System simulates a two-dimensional system of particles confined between a thermal reservoir and a piston. This computer model is designed to study the equation of state for hard disks without other interactions. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. Users can set the initial particle energy, the initial particle separation, and the thermal reservoir temperature Tr. The thermal conductivity parameter ? determines the probability that a collision with the thermal wall will affect (thermalize) the colliding particle. If the conductivity is one, the particle velocity after a reservoir collision is set according to Maxwell-Boltzmann statistics. If the conductivity is zero, all reservoir collisions are elastic and the internal energy E of the system is conserved.
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- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 922 KB
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- Platform: WinOther
- Lennard-Jones PVT System Model for Windows
- License: Freeware
- Price: 0.00


The Lennard-Jones PVT System simulates a two-dimensional system of particles confined between a thermal reservoir and a piston. This computer model is designed to study the equation of state for particles interacting via a simple but realistic molecular potential that has a weak long-range attraction and a strong short range repulsion. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. Users can set the initial particle energy, the initial particle separation, and the thermal reservoir temperature Tr. The thermal conductivity parameter ? determines the probability that a collision with the thermal wall will affect (thermalize) the colliding particle. If the conductivity is one, the particle velocity after a reservoir collision is set according to Maxwell-Boltzmann statistics. If the conductivity...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 963 KB
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- Platform: WinOther
- Linear Charge Gauss's Law Model
- License: Shareware
- Price:


The EJS Linear Charge Gauss's Law model shows a Gaussian surface and allows for the measurement of the charge enclosed and surface area of the surface. Users can change the radius of the linear charge as well as the size of the Gaussian surface. Users can modify this simulation if Ejs is installed.
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.
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1423 KB
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- Platform: WinOther
- Oscillator Chain Model
- License: Freeware
- Price: 0.00


The EJS Oscillator Chain model shows a one-dimensional linear array of coupled harmonic oscillators with fixed ends. This model can be used to study the propagation of waves in a continuous medium and the vibrational modes of a crystalline lattice. The Ejs model shown here contains 31 coupled oscillators equally spaced within the interval [0, 2 pi] with fixed ends.
Ejs Oscillator Chain 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_mech_osc_OscillatorChain.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 for classical mechanics are available. They can be found by...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1126 KB
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- Platform: WinOther
- QM Superposition Program
- License: Freeware
- Price: 0.00


The QM Superposition program displays the time evolution of the position-space wave function. The default wave function shows a two-state superposition of harmonic oscillator states. Additional states and other potential energy functions can be specified using the Display | Switch GUI menu item.
QM Superposition is one of 18 Open Source Physics programs that model time-dependent quantum mechanics using an energy eigenstate expansion. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the qm_superposition.jar file will run the program if Java is installed. Other programs provide additional visualizations. They can be found by searching ComPADRE for Open Source Physics, OSP, or Superposition.
Please note that this resource requires at least version 1.5 of Java.
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 593070 KB
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- Platform: WinOther
- Rotation About a Fixed Axis Model for Windows
- License: Freeware
- Price: 0.00


The Rotation About a Fixed Axis example computes the angular momentum of a rigid rectangular box attached to a rotating axle. The fixed axis is in the z-direction. Users can tilt the box relative to the axle and can change the box dimensions. The simulation shows that the angular momentum vector L is not aligned with the the angular velocity vector unless the box is rotating about an axis parallel to a box edge. The simulation also shows the torque N that must be applied to the axle to maintain its fixed orientation. Additional windows display the frame-dependent tensor algebra in an inertial reference frame fixed in space and in a non-inertial reference frame attached to the rotating box with a rotation axis parallel to a box edge.
The Rotation About A Fixed Axle model was developed using the Easy Java Simulations (EJS)...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 856 KB
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- Platform: WinOther
- Simple Pendulum Model
- License: Freeware
- Price: 0.00


The Ejs Simple Pendulum model displays the dynamics of a simple pendulum. The pendulum is initially displaced from equilibrium and the pendulum bob has zero initial velocity. The initial position of the pendulum bob can be changed by click-dragging the bob when the simulation is paused. 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.
Ejs Simple Pendulum 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_osc_Pendulum.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 for...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1331 KB
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- Platform: WinOther
- Spheres of Eudoxus Model
- License: Freeware
- Price: 0.00


Spheres of Eudoxus model simulates the system devised by the Ancient Greek astronomer Eudoxus to model the motion of the planets. The model consists of four nested concentric spheres. The axis of each sphere is attached to the surface of the next sphere out. The planet itself is located on the surface of the innermost sphere. The outermost sphere rotates with the daily (apparent) rotation of the stars.
The Spheres Frame shows the four spheres of the model. The axis of the inner (red) sphere can be tilted relative to that of the middle (blue) sphere using a slider to adjust the angle. The red sphere automatically rotates with angular velocity +1.0 (in arbitrary units). The angular velocities of the blue and green spheres can be adjusted using sliders. Note that the axis of the blue sphere is attached to the equator of the...
- Publisher: Wolfgang Christian
- Date Released:
- Download Size: 1280 KB
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- Platform: WinOther
