The EJS Classical Helium Model is an example of a three-body problem that is similar to the gravitational three-body problem of a heavy sun and two light planets. The important difference is that the helium atom's two electrons repel one another, unlike the planetary case where the intraplanetary interaction is attractive.

The Colliding Galaxies Model is an implementation of Alar and Juri Toomres' 1972 super computer model showing the formation of galactic bridges and tails under the assumption that galactic cores are point masses and that one galactic core is surrounded by 2D concentric rings of orbiting stars. The model assumes is that the stars (test particles) orbiting the galactic cores are non-interacting. When the two galaxies pass one another, tidal forces deform the star distribution into classic tidal features. Our EJS model reproduces this result showing that there is a long curving tail and that only the outermost ring of stars is affected by its companion galaxy. A thin bridge is also formed and some of the stars are captured by the companion galactic core.

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. Version 4.1 adds grouping and affine transformations to 2D drawing Elements.

The EJS Energizer model explores the relationship between kinetic, potential, and total energy. Users create a potential energy curve and observe the resulting motion.

The Fourier sine series model displays the sine series expansion coefficients of an arbitrary function on the interval [0, 2?].

A Galton board is a vertical board with n rows of pegs onto which a ball is dropped.  Each time a ball hits a peg, it has a probability p of bouncing to the left and a probability of 1-p of bouncing to the right. The simulation's histogram shows the distribution of x-coordinates as the balls leave the board and are collected into bins. The simulation gives rise to the binomial distribution if the probabilities of left and right bounces are equal. At first there does not seem to be any pattern but after many trials the familiar "bell curve" shape begins to emerge.

Basic concepts of computer modeling in science and engineering using discrete particle systems and continuum fields. Techniques and software for statistical sampling, simulation, data analysis and visualization. Use of statistical, quantum chemical, molecular dynamics, Monte Carlo, mesoscale and continuum methods to study fundamental physical phenomena encountered in the fields of computational physics, chemistry, mechanics, materials science, biology, and applied mathematics. Applications drawn from a range of disciplines to build a broad-based understanding of complex structures and interactions in problems where simulation is on equal-footing with theory and experiment. Term project allows development of individual interest. Student mentoring by a coordinated team of participating faculty from across the Institute.

The Linear Congruent Number Generator Model The method generates a sequence of integers xi over the interval [0, m-1] by the recurrence relation
x[i+1] = (ax[i]+c) mod m
Where the modulus m is greater than zero, the multiplier a is greater than zero and less than m, and the increment c is greater than zero and less than m. All numbers are integers and all arithmetic is integer arithmetic. The initial value x0 is known as the seed. 

The butterfly-like Lorenz attractor is a simplified model of two-dimensional convective fluid flow and is one of the best known images of chaos. Embedded in this attractor are unstable periodic orbits described by Viswanath and this model computes a number of these orbits. Each periodic orbit is classified by the number of times the trajectory orbits the A and B fixed points before it repeats. Note that because the attractor is chaotic and because of numerical errors and the finite precision of the initial conditions, errors accumulate and the trajectory leaves the vicinity of a periodic orbit after a half dozen cycles.

This Java archive contains a collection of simple Easy Java Simulations (EJS) programs for the teaching of computer-based modeling. The materials and text of this resource appeared in an article of the same name in The Physics Teacher [Phys. Teach. 76, No. 45, pp. 474-480 (2007)].

Modeling a Changing World written by mathematics professor Tim Chartier and his student Nick Dovidio presents curricular material in an OSP Launcher package to motivate the need for numerically solving ordinary differential equations. The package discusses such applications as a mass-spring system and its connection to computer simulation for movies. An interactive model that simulates a two-body gravitational model of the moon and earth allows for exploring the topic of numerical error. Other models explore topics that include slope fields, numerical integration and numerical solvers for ordinary differential equations.

Python is a programming language that is increasingly being used for computation in physics. Why is this? Python is easy to learn. Python is a modern interpreted object-oriented language. Python programs are simple, clean, and easily readable. Python has a wide range of support packages or program libraries useful for numerical computation.

The EJS Roller Coaster model explores the relationship between kinetic, potential, and total energy as a cart travels along a roller coaster. Users can create their own roller coaster curve and observe the resulting motion.

The STP Eclipse Workspace contains a ready to use Eclipse worksapce with source code for Statistical and Thermal Physics (STP) programs by Jan Tobochnik and Harvey Gould. Unzip this workspace and open it from within Eclipse to compile and run these programs.

The Scalar Field Gradient Model displays the gradient of a scalar field using a numerical approximation to the partial derivatives. This simple teaching model also shows how to display and model scalar and vector fields using EJS.