Double Rayleigh Model

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...

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...

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 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...


Platforms: Mac

The Eratosthenes model displays the shadows cast by two gnomons (sticks) at different locations on Earth. For one gnomon, Sun is directly overhead (as would be the case if the gnomon was on the Tropic of Cancer at the summer solstice). The other gnomon is due north of the first gnomon. The sizes...


Platforms: Mac

The EJS Magnetic Multipole Field Model shows the field of a magnetic dipole or quadrupole with little compasses that indicate direction and relative field strength. A slider changes the angular orientation of the dipole and a movable compass shows the magnetic field direction and magnitude....


Platforms: Mac

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...


Platforms: Mac

The Orbits Within Spherical Galaxies model displays the two-dimensional trajectories of particles (stars) within a galaxy having a spherically symmetric mass distribution that heuristically approximates the distributions found in galaxies and bulges. The model uses a mass density proposed by...


Platforms: Mac

The Light and Shadow Model shows light that either passes through a mask with a hole in it, or it is blocked by an object, as it travels to a screen on the right. The user can turn on and off two light bulbs (red and blue) and drag the bulbs around the screen to change their positions....


Platforms: Mac

The Ejs Quartic Potential Orbit model displays the dynamics of a mass orbiting a much larger mass subject to a quartic potential, C/r4. The simulation displays the motion of the smaller mass and the effective potential energy diagram. The initial energy of the system can be changed via textbox...


Platforms: Mac

The Three State Nuclear Decay model extends the Two State Nuclear Decay model to simulate the radioactive decay of atomic nuclei in which the parent nucleus first decays into an intermediate state before decaying into a stable state. Although the decay of both the parent and intermediate nucleus...


Platforms: Mac

The EJS Waveguide model displays the motion of a traveling wave forced to move between two walls in a waveguide. The two walls are located at y = 0 and a, so that its normal modes are u(t,x) = A sin(n ?Y?* y/a) cos(k x - ?Ya* t) with n equal to a positive integer. The phase velocity and number of...


Platforms: Mac

The Ejs Great Circles model displays the frictionless motion of a particle that is constrained to follow the surface of a perfect sphere. The sphere rotates underneath the particle, but since there is no friction, and the sphere is perfectly spherical, the motion of the particle is not influenced...


Platforms: Mac

The Ejs Superior Ptolemaic model illustrates Ptolemy's orbit for a superior planet. The model consists of a deferent circle, centered on a point some distance from Earth (at the eccentric point). Attached to this deferent is the center of another circle, the epicycle. The center of the epicycle...


Platforms: Mac

The Ejs Action for the Harmonic Oscillator model displays the trajectory of a simple harmonic oscillator by minimizing the classical action. The simulation displays the endpoints of the motion (t,x) which can be changed by using the textboxes or dragging, and displays the new trajectory as well...


Platforms: Mac

The Ejs Copernican System model illustrates Copernicus' system of planetary motions. The entire system is centered on the center of Earth's uniform, circular orbit. Sun is placed near, but not at, this center point. The orbit of each planet (other than Earth) consists of a deferent circle,...


Platforms: Mac

The Ejs Inferior Ptolemaic model illustrates Ptolemy's orbit for a inferior planet. The model consists of a deferent circle, centered on a point some distance from Earth (at the eccentric point). Attached to this deferent is the center of another circle, the epicycle. The center of the epicycle...


Platforms: Mac

The Magnet Falling Through Ring model shows the dynamics and the induced current when a magnet falls through a conducting ring. The current in the ring is computed by electromagnetic induction using to Faraday's law and the induced emf is proportional to the negative of the rate of change of...


Platforms: Mac

The Einstein Cannon model computes and displays the trajectory of cannonballs (particles) shot from a cannon in the vicinity of a black hole. It was created for the study of Einstein's theory of general relativity and the Schwarzschild metric. The main window displays a map of space in the...


Platforms: Mac

The Particle Worldline model computes and displays the trajectory of a test particle in the vicinity of a black hole using Schwarzschild coordinates. It was created for the study of Einstein's theory of general relativity and the Schwarzschild metric. The model has input fields displaying the...


Platforms: Mac