Samantha Harris Model

The Ejs Spring Pendulum model displays the model of a hollow mass that moves along a rigid rod that is also connected to a spring. The mass, therefore, undergoes a combination of spring and pendulum oscillations. The initial position and velocities, as well as the spring constant can be changed...

The Pendulum Motion Model shows the motion of a simple pendulum. You can change the mass of the pendulum bob, the length of the string, the acceleration due to gravity, and the initial position of the pendulum. You can then see the resulting motion of the pendulum, as well as see bar graphs of...

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 Ikeda Delay Differential Equation model shows the dynamics of a delay differential equation that depends on the value of the dynamical variable x(t) at a previous time x(t-?). Sprott shows that these systems provide elegant examples of chaos in systems that are too simple to exhibit chaos...


Platforms: Mac

The Ejs Two Falling Rods model displays the dynamics of two rods which are dropped on a smooth table. In one case the end point on the table slides without friction, while in the other case it rotates about a pivot point. The simulation allows computing fall times and trajectories. The initial...


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 Car Race model is a Java-based simulation that will help students visualize the difference between constant velocity and constant acceleration. It features the classic physics scenario in kinematics: a lead car travels at constant velocity on a straight track, while a second car moves from...


Platforms: Mac

The Three Point Charges is an inquiry-based model for exploring the force between charged objects. Initially, the simulation sets up three charged objects, one at each corner of an equilateral triangle. The charges have different magnitudes, represented by force vectors. The charges can be moved,...


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 Three Current-Carrying Wires model is a ranking task exercise involving the ranking of the current magnitudes in three parallel current-carrying wires. The simulation displays the net force on each wire because of the other two wires. You can modify this simulation if you have Ejs...


Platforms: Mac

The EJS Slipping and Rolling Wheel Model shows the motion of a wheel rolling on a floor subject to friction. The simulation allows the user to change the initial translational and rotational velocities of the wheel, v and ?Ya*, the mass, radius, and mass distribution, R, m, and C of the wheel. By...


Platforms: Mac

The Falling Cup with Ball model shows a mass attached to the inside of a cup with a light spring. The cup is held upside down with the mass hanging out of the cup, then released from rest. What happens when the cup is released? 1. The mass will extend the spring, like a parachute, due to air...


Platforms: Mac

The Ejs Wave Packet model displays the motion of an approximate wave packet. The simulation allows an arbitrarily wave packet to be created. The default dispersion relation, with the frequency equal to the wavenumber, results in a wavepacket that does not spread. The amplitude, maximum and...


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 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...


Platforms: Mac

The EJS Earth Orbit 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 Sphere....


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