Ejs

The Driven Wave Machine model simulates a wave machine driven by a sinusoidal oscillator. The machine consists of horizontal bars welded to a torsion rod that is perpendicular to the bars. The simulation allows the user to change the number of bars, the drive frequency, and the boundary...

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,...

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 Local Coordinates model displays the position of a star in local (Altitude/Azimuth) coordinates. The horizon is shown along with the four cardinal directions (N, E, S, and W). The latitude of the observer is set at 35.5 degrees which sets the location of the north celestial pole (teal)...


Platforms: Mac

The Ejs Wave Representations model displays two representations of a sinusoidal wave on a string. One shows a movie of the wave traveling along a string - you can think of this representation as a sequence of photographs. The second representation is a plot of the displacement as a function of...


Platforms: Mac

The Ejs Two Orbiting Masses with Relative Motion model displays the dynamics of two masses orbiting each other subject to Newtonian gravity. The simulation displays the motion of the masses in the inertial reference frame and the relative motion as seen from one of the masses. The initial energy...


Platforms: Mac

The Circular Well model displays the 2D energy eigenstates of a particle trapped in a very deep two-dimensional circular well. Because the Schr?*A*dinger equation for this system is separable into radial and angular differential equations, the solution can be expressed as a product of a Bessel...


Platforms: Mac

The Ejs Non-Newtonian Orbit model displays the dynamics of a mass orbiting a much larger mass subject to non-Newtonian gravity. 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 and the...


Platforms: Mac

The Ejs Duffing Poincare model computes the solutions to the non-linear Duffing equation, which reads, x'' + 2?zN*x' - x (1 - x2) = f cos(?Ya* t), where each prime denotes a time derivative. The simulation displays the solution Poincare plot. The evolution parameters can be changed via textboxes....


Platforms: Mac

The Spring Motion Model shows the motion of a block attached to an ideal spring. The block can oscillate back-and-forth horizontally. You can change the mass of the block, the spring constant of the spring, and the initial position of the block. You can then see the resulting motion of the block,...


Platforms: Mac

The Thin Film Interference model investigates reflection and transmission of light through a thin film. The user can change the thickness and index of refraction of the thin film as well as the incident light wavelength. The Thin Film Interference Model was created using the Easy Java...


Platforms: Mac

The Ejs Platform on Two Rotating Cylinders model displays the model of a platform resting on two equal cylinders are rotating with opposite angular velocities. There is kinetic friction between each cylinder and the platform. The separation between the cylinders and the coefficient of kinetic...


Platforms: Mac

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...


Platforms: Mac

The EJS Galileo Sunspots Model illustrates the motion and changes in appearance of sunspots as they move across the disk of the Sun. Galileo's observation of the changing appearance of sunspots around 1611 provided strong evidence that the spots were actually blemishes on the surface of the Sun,...


Platforms: Mac

The Ptolemy/Copernicus/Tycho EJS Model illustrates the relationships between the systems of planetary astronomy developed by Claudius Ptolemy, Nicholas Copernicus, and Tycho Brahe. The model presents a simplified version of all three systems, showing the motions of the Sun/Earth and two planets...


Platforms: Mac

The EJS Herschel's Star Gages Model illustrates William Herschel's methods of "star gages" by which he attempted to map out the shape of our galaxy in 1785. Herschel's star gages (sic) relied on two important assumptions: that Herschel's telescope (his "large 20 foot" with an 18.5 inch aperture)...


Platforms: Mac

The EJS Shapley's Globular Clusters Model shows the distribution of globular clusters around the plane of the Milky Way as determined by Harlow Shapley in 1918. The Space View frame shows a 3D view of the distribution of the clusters around the galactic plane, along with the location of the Sun...


Platforms: Mac

The EJS Differential Galactic Rotation Model illustrates the model of galactic rotation proposed by Jan Oort in 1927. In Oort's model most of the mass of the galaxy is concentrated at the center. Stars move in circular orbits around the center, with orbital speeds that are inversely proportional...


Platforms: Mac

The EJS Parallactic Proper Motion Model illustrates the phenomenon known as parallactic proper motion. Proper motion refers to the progressive (non-oscillatory) apparent motion of a star relative to more distant background stars. If this apparent motion is due to actual motion of the star through...


Platforms: Mac