Linear Model

The Ejs Celestial Globe model simulates the Two Sphere Universe theory of the Ancient Greeks. This theory supposes the stars to be fixed on the surface of a Celestial Sphere, with the spherical Earth at the center of this sphere. The simulation shows the motion of Sun and stars in this model, as...

The Ejs N-body Orbits model displays the dynamics of three to five identical masses orbiting each other subject to Newtonian gravity. The simulation displays the periodic orbital motion of the masses. The initial configuration of the system can be changed via slider. You can modify this...

The Ejs Doppler Effect model displays the detection of sound waves from a moving source and the change in frequency of the detected wave via the Doppler effect. In addition to the wave fronts from the source a graph depicting the time of emission and time of detection of each of the wave fronts...


Platforms: Mac

The Ejs Circumnavigating Pendulum model displays the dynamics of a mechanical oscillator in uniform circular motion. The mechanical oscillator is free to move in two directions. This 2-dimensional simulation displays all the dynamical features of the Foucault pendulum, except for the dependency...


Platforms: Mac

The Rocking Semicircular Hoop model shows the dynamics of a simple object rocking without slipping on a horizontal surface. It is a supplemental simulation for an article by Leaf Turner and Ari Turner "Asymmetric rolling bodies and the phantom torque" in the Am. J. Phys. 78, 905 (2010). The...


Platforms: Mac

The Ejs Orbiting Mass on a Table 3D model displays the frictionless dynamics of two masses that are attached via a string through a hole in a horizontal table. Mass m moves on the table in two dimensions while mass M hangs vertically and just moves up and down. The simulation allows displaying...


Platforms: Mac

The Ejs Driven Diatomic Oscillator Chain model displays a one-dimensional diatomic chain of coupled harmonic oscillators with one end driven by an external force and the other end attached to a sliding rod shock absorber. The mass and Stoke's Law damping for the shock absorber are chosen to...


Platforms: Mac

The Heating and Cooling a Cylinder model computes the radial temperature distribution within a long cylinder as it is heated and cooled by a surrounding fluid. The cylinder is broken into shells and the temperature of each shell is computed using a finite difference approximation to the radial...


Platforms: Mac

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...


Platforms: Mac

The Ejs Phase Space Plotter model displays the dynamics of an ensemble of pendula or simple harmonic oscillators in phase space (velocity versus position). Friction is initially set to zero but can be changed via a textbox as can the number of elements in the ensemble. For the pendulum ensemble,...


Platforms: Mac

The Point Charge Forces in One-Dimension model investigates the electric force that one charged particle exerts on another. It is a very simple representation that promotes understanding of Coulomb's Law in three ways: First, students can set the amount of charge on each particle and view vector...


Platforms: Mac

The Ejs Lagrange Top model displays the motion of a heavy symmetric top under the effect of gravity. The top has an initial angular speed that provides the precessional, nutational, and rotational speeds. The ratio of Lz to Lx can be set via slider and the initial angular position and angular...


Platforms: Mac

The Simultaneity Spacetime Diagram model uses light-trajectories to show the effect of relative motion when observing (recording) events in special relativity. In the default scenario, an explosion (an event) at the center of a right-moving stick occurs at t=0 and the arrival of the explosion...


Platforms: Mac

The EJS Molecular Dynamics model is constructed using the Lennard-Jones potential truncated at a distance of 3 molecular diameters. The motion of the molecules is governed by Newton's laws, approximated using the Verlet algorithm with the indicated time step. For sufficiently small time steps dt,...


Platforms: Mac

The Ejs Foucault Pendulum model displays the dynamics of a Foucault pendulum. The simulation is designed to show the dynamical explanation of why precession of the Foucault pendulum is slower at lower latitudes. The simulation shows simultaneously the motion with respect to the inertial...


Platforms: Mac

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...


Platforms: Mac

The Ejs Inertial Oscillation model displays the motion of a particle moving over the surface of an oblate spheroid. The spheroid is flattened to an ellipsoid of revolution because it is rotating, just as the Earth is flattened because it is rotating. The particle is confined to motion along the...


Platforms: Mac

The EJS Equinox Precession model illustrates the Copernican theory of Earth's orbit around the sun. The top window shows a view from outside the celestial sphere. The simulation shows the moving Earth along with its axis or rotation and the line of sight from Earth, through Sun, to the Celestial...


Platforms: Mac

The Ejs Coin Rolling without Sliding on an Accelerated Platform model displays the dynamics of a coin rolling without slipping on an accelerated platform. The simulation displays the motion of the coin as well as the velocity vectors for the surface of the coin and the platform. The initial...


Platforms: Mac

The Ejs Damped Driven Harmonic Oscillator Phasor model displays the motion of damped driven harmonic oscillator. The resulting differential equation can be extended into the complex plane, and the resulting complex solution is displayed with the real part of this solution being the position of...


Platforms: Mac