Logistic Growth Model Curves

The Ejs Hard Sphere Gas model displays a three-dimensional (ideal) gas made out of hard disks. Particles are initialized with a random speed and in a random direction and move with constant velocity until a collision occurs. You can modify this simulation if you have Ejs installed by...

The Newton's Law of Cooling model computes the temperature of an object of mass M as it is heated by a flame and cooled by the surrounding medium. The model assumes that the temperature T within the object is uniform. This lumped system approximation is valid if the rate of thermal energy...

The EJS Cellular Automata (Rule 90) model displays a lattice with any one of a finite number of states which are updated synchronously in discrete time steps according to a local (nearby neighbor) rule. Rule 90 is a specific nearby neighbor rule following the classification scheme developed by...


Platforms: Mac

The Ejs Harmonics and Fourier Series model displays the sum of harmonics via a Fourier series to yield a new wave. The amplitude of each harmonic as well as the phase of that harmonic can be changed via sliders. In addition, several pre-set functions can be chosen to display. You can modify this...


Platforms: Mac

The Ejs Free Fall model displays the dynamics of a ball dropped near the surface of Earth onto a platform. The initial conditions for the ball are zero initial velocities in the x and y directions. The coefficient of restitution for the ball's collision with the platform is less than one. The...


Platforms: Mac

The Binomial Coefficient model displays the number of ways k objects can be chosen from among n objects when order is irrelevant. This number is known as a binomial coefficient and can be used to predict the the flipping of n coins with equal probability of heads and tails. The Binomial...


Platforms: Mac

The Falling Slinky model approximates a slinky using twenty masses connected with light springs. The slinky is suspended from one end and released. Two actions will occur simultaneously when it is released hanging at rest from its equilibrium position - it will fall and it will collapse. What...


Platforms: Mac

The EJS Binomial Distribution Model calculates the binomial distribution. You can change the number of trials and probability. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. The Binomial...


Platforms: Mac

The Ejs First Law model displays the dynamics of a ball subject to no net force. The initial conditions for the ball are an initial velocity in the x and y directions. The initial position of the ball can be changed by dragging it when the simulation is paused. You can modify this simulation if...


Platforms: Mac

This computer model allows students to split a vector into its components and practice finding the magnitude and direction. In addition, it offers a "Find components" mode, where magnitude and direction of the vector are given and the student's task is to find the x-component and the y-component...


Platforms: Mac

The Ejs Coupled Oscillators and Normal Modes model displays the motion of coupled oscillators, two masses connected by three springs. The initial position of the two masses, the spring constant of the three springs, the damping coefficient for each mass, and the driving force and driving force...


Platforms: Mac

The Kepler System model simulates Kepler's final theory of planetary motion. In this theory the planets orbit in ellipses with Sun at one focus (Kepler's First law). These elliptical orbits are not necessarily all in the same plane. A line from Sun to the planet sweeps out equal areas in equal...


Platforms: Mac

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...


Platforms: Mac

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...


Platforms: Mac

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 Rectangular Well model displays the 2D energy eigenstates of a particle trapped in a very deep two-dimensional rectangular well. Because the Schr?*A*dinger equation for this system is separable into one-dimensional infinite square well Hamiltonians, the solution can be expressed as a product...


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