New Open Source Physics collection resources
https://www.compadre.org/OSP/
The latest material additions to the Open Source Physics.en-USCopyright 2021, ComPADRE.orgopensourcephysics@compadre.orgopensourcephysics@compadre.orgTue, 16 Feb 2021 13:10:10 ESThttp://blogs.law.harvard.edu/tech/rsshttps://www.compadre.org/portal/services/images/LogoSmallOSP.gifOpen Source Physics
https://www.compadre.org/OSP/
12535Relativistic and Newtonian World Lines JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15572
The Relativistic and Newtonian World Lines JavaScript model simulates the motion of a particle in two inertial frames, and in the context of two different theories: a) the Einstein's Special Relativity and b) the Newtonian Mechanics.
In the initial frame (O) the user can choose two motions for the particle: a) a uniform linear, or b) a uniform circular. These choices are accomplished by pressing the button at the end of the text: "Linear world line"/"Circular world line". The left windows depict the motions in the (O) frame, and the right in the (O') frame. The origin O of the (O) frame is moving with respect to the (O') frame along the x-axis with velocity v0, controlled by the user. For the case of the linear motion, the particle's velocity magnitude and the angle forming with x-axis in (O) frame, are also selected by the user. The corresponding values in the (O') frame are given by the output tools in the control panels of the simulation. The clocks attached in every window measure the world time for the corresponding inertial frame, and the particle's time coordinate.Relativity/Spacetime Fundamentals/World Lineshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15572Tue, 16 Feb 2021 13:10:10 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15572Relativistic and Classical Particle Collision Comparison JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15568
The Relativistic and Classical Particle Collision Comparison JS Model shows a two-particles collision, according to two models: a) a relativistic model and b) a Newtonian model. The primary objective is to signify and compare the predictions of the two theories on the particular phenomenon.
The system is composed of two classical particles P1 and P2. P2 at rest at the origin O of the LS. P1 is moving toward P2 with velocity v0 along the x-axis. The initial conditions of the system and the parameters determining the interaction machinery between the particles are identical in the two models. The particles are distinct: they preserve their masses before and after the interaction. The collision is elastic: the total momentum and energy are kept invariant.Relativity/Special Relativity/Relativistic Kinematicshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15568Wed, 20 Jan 2021 08:29:35 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15568Relativistic and Newtonian Oscillator Comparison JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15562
The Relativistic Plane-Oscillator JS Model compares the motion of a Newtonian and a relativistic plane oscillator. The comparison of the two motions shows that the path of the relativistic oscillator, although plane and localized, is not in general, a closed curve like the corresponding path in the Newtonian model.
A supplemental document describing the theory and related exercise is provided.Relativity/Special Relativity/Relativistic Kinematicshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15562Sun, 06 Dec 2020 16:23:26 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15562Elastic Wave on a String JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15560
The Elastic Wave on a String JS Model shows the motion of a mechanical system consisted of an oscillator attached at the edge of a semi-infinite elastic string. The oscillator creates a disturbance on the string that moves along the string as an elastic wave. Energy is transferred from the oscillator to the string resulting in a dissipation effect on the motion of the oscillator; the motion of the oscillator is a damped oscillation.
A supplemental document presents the model's theory using a Lagrange function to model a chain of coupled oscillators and the principle of least action.Oscillations & Waves/Wave Motion/Transverse Pulses and Waveshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15560Tue, 03 Nov 2020 14:43:56 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15560Charged Particle Scattering in a Central Field JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15558
Scattering in a Central Field simulates the scattering of N identical but distinct positive charged particles in a central electrostatic field. The simulation shows the paths of the particles and a circular screen where the particles impact. The impact parameter of each particle and the corresponding scattering-angle are calculated in real-time and recorded in the cells of a data table, attached to the virtual environment. The scattering angle is a function of the impact parameter.
The analytic expression of the scattering angle function depends on the structure of the target producing the field. From the recorded data the user can make models concerning the structure of the target, and then design and implement the appropriate experiments aiming at the confirmation of his or her conjectures. The supplemental pdf document summarizes the theory and provides exercises and activities for students.Classical Mechanics/Motion in Two Dimensions/Central Forceshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15558Sun, 25 Oct 2020 17:31:21 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15558Tracker Video Analysis and Modeling JS (Beta)
https://www.compadre.org/OSP/items/detail.cfm?ID=15557
The JavaScript implementation of the Tracker Video Analysis and Modeling Tool is now available for beta testing. This online program runs within a web browser that supports HTML5 + JavaScript. It allows users to drag and drop Tracker Experiment files or video clips onto the web page to analyze the motion of objects in videos. By overlaying simple dynamical models directly onto videos, students may see how well a model matches the real world. Interference patterns and spectra can also be analyzed.
The original Tracker Java program was written by Doug Brown at Cabrillo College using portions of the the Open Source Physics code library developed by Wolfgang Christian at Davidson College. Tracker was later converted from Java to JavaScript by Doug Brown, Wolfgang Christian and Robert Hanson using the SwingJS system developed by Hanson and his students at St. Olaf College.
Additional Tracker resources, including Tracker help and sample videos, are available from the <a href="https://physlets.org/tracker/">Tracker website</a>.General Physics/Generalhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15557Mon, 12 Oct 2020 16:28:51 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15557Diffusion of a 2D Gas JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15556
The Diffusion of a 2D Gas JS Model shows a 2D rectangle-shaped container is 2L long and L high that is divided into two equal square chambers D1 and D2 by a diaphragm. In the middle of the diaphragm, there is a gap of height h which is initially closed by a barrier. In the container, there are N identical but discrete particles. The particles interact in pairs. During each interaction, the momentum and energy of the pair are conserved. The interactions of particles with the walls of the container are elastic collisions.
At time t=0 all particles are in the left compartment D1 and have random positions and velocities. The initial velocity distribution of the gas, although it is not identical to the Maxwell-Boltzmann distribution, it is very "near" to this and, because of the p-p interactions, it converges extremely fast to it. Over time, particles are transferred through the gap from D1 to D2 and vice versa, so that the numbers of particles n1 and n2 in each chamber are changing. Over time, particles are transferred through the gap from D1 to D2 and vice versa, so that the numbers n1, n2 of particles in each chamber are changing. The program counts n1, n2 in real time and draws their graphs with time. On the other hand, a mathematical model has been composed, by which the variation of n1 and n2 is calculated over time and the corresponding graphs are depicted. The user compares the theoretical graphs with the experimental.
The user can select the values of the length h of the gap and the mean energy of the particles. He can also adjust the value of a statistical-phenomenological parameter, so that the agreement of the experimental data with the theoretical graphs be the best possible.Thermo & Stat Mech/Kinetic and Diffusive Processes/Diffusionhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15556Wed, 07 Oct 2020 09:31:18 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15556Binary Star System with Lorentz Symmetry Violating Effects
https://www.compadre.org/OSP/items/detail.cfm?ID=15555
The EJS Binary Star System with Lorentz Symmetry Violating Effects 3D Model illustrates the effects of violations in Lorentz symmetry to any detached binary star system. Lorentz symmetry is defined as the similar observation of the laws of physics within different inertial reference frames. The Standard-Model-Extension (SME) is used to search for violations of Lorentz symmetry with the hopes of discovering evidence of new laws within physics. A detection of Lorentz symmetry violation would come when an accepted law of physics is broken after a frame’s orientation is rotated or accelerated. We can visualize these effects as though there is a background tensor field permeating through space that will change the fundamental physical laws we currently hold as true.
This simulation allows the user to input any initial conditions (i.e. masses, orbital periods, etc.) for a binary star system and observe the evolution of the stars’ orbits. Similarly, the user can alter the values of the SME coefficients (c_jk background tensor field values). Whenever these coefficients are zero, the binary star system will behave as predicted, effected only by the gravitational force they exert on each other. However, when the SME coefficients are nonzero the orbits of the stars evolve in a way such that the net force on the stars is no longer parallel to the acceleration of the stars. Additionally, with nonzero c_jk values, the total angular momentum of the system is no longer conserved.
Astronomy/Stars/Binary Starshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15555Thu, 17 Sep 2020 12:15:54 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15555Osmosis in a 2D Gas JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15554
The Osmosis in 2D Gas JavaScript Model shows a hard disk gas in a container with a semi-permeable barrier in which N particles are moving. The particles are discriminated into two classes: The "red" particles which cannot pass through the barrier and they are always trapped in chamber D1 and the "blue" particles which can pass through the barrier and move everywhere in the container. The number of "red" particles is n_r=N/3 and that of the "blues" is n_b=2N/3. At time t=0, there are equal numbers of particles in D1 an D2: N/3 "reds" and N/6 "blues" in D1 and N/2 "blues" in D2. Hence the pressure of the gas in each chamber is the same. But, because of the inability of the red particles to pass through the barrier, the number of particles in D1 gradually increases, and that of the particles in D2 decreases. As a result, the pressure in D1 increases with time, and the pressure in D2 decreases by the same amount. This process continues until the system reaches in a state of dynamical equilibrium, achieved when the number of "blue" particles is the same in both chambers. In the state of dynamical equilibrium, the total numbers of particles in each chamber are different. This implies that the final pressure in D1 is different than the pressure in D2; their difference is defined as the osmotic pressure of the system.
The simulation records the number of particles in each chamber, at a specific sequence of time moments, and calculates the corresponding pressures, in real time. In parallel, for every time-step of the simulation, the program calculates the theoretical values of the particles' numbers and the pressures in D1 and D2 derived by the theoretical model, and the corresponding graphs are composed.Thermo & Stat Mech/Thermal Properties of Matterhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15554Tue, 15 Sep 2020 13:11:55 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15554Ising JS Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15451
The Ising JavaScript simulation implements a simple nontrivial model that has a phase transition and is one of most important models in statistical mechanics. The model consists of spins located on a lattice such that each spin can take on one of two values designated as up and down or ±1. The interaction energy between two neighboring spins is -J if the two spins are in the same state and +J if they are in opposite states. The Ising model undergoes a phase transition between an ordered and a disordered phase in two dimensions or more.
The Ising Model program was developed by Wolfgang Christian at Davidson College using the Open Source Physics Java code library. It is based on a Java program from <em>An Introduction to Computer Simulation Methods</em>. It was converted from Java to JavaScript using the system developed at St. Olaf College and Robert Hanson.Thermo & Stat Mech/Models/Ising Modelhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15451Sat, 22 Aug 2020 08:06:40 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15451Boltzmann H-theorem: Approaching Equilibrium Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15448
The purpose of the application is to depict the evolution of a 2D toward its equilibrium state and test experimentally the Boltzmann H-theorem.
In the sim-window the user can see the motion and the interactions of the gas-particles. The initial distribution is chosen by the user among three alternatives. In the graphs which are composed in real time, the user can see the evolution of the particles' velocity distribution and the variation of the Boltzmann functional H. The convergence of the distribution to the Maxwell-Boltzmann distribution irrespectively of the initial one is impressive. In the H-graph the user can notice the convergence of H to its minimum value corresponding to the Maxwell-Boltzmann distribution.
The applet is accompanied by an extensive analysis of the background theoretical model.Thermo & Stat Mech/First Law/Thermal Equilibriumhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15448Wed, 19 Aug 2020 11:48:40 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15448STP CoinToss JS Simulation
https://www.compadre.org/OSP/items/detail.cfm?ID=15445
Program <tt>CoinToss</tt> models the repeated tossing of a single coin or the tossing of a large number of identical coins at the same time. The goal of this simulation is to see how the percentage of times that you obtain heads fluctuates and to obtain some feel for how close you come to the expected average after $N$ tosses of a single coin or the toss of $N$ coins at one time.
The STP CoinToss program shown here was converted from Java to JavaScript by Wolfgang Christian and Robert Hanson (St. Olaf College) using the SwingJS system developed at St. Olaf College.Thermo & Stat Mech/Probability/Binomial Distributionhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15445Wed, 12 Aug 2020 14:52:41 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15445SwingJS: EJS Java to JavaScript Conversion Examples
https://www.compadre.org/OSP/items/detail.cfm?ID=15444
It was believed that the entire enterprise that had grown around embedding Java simulations in web pages had come to an end when the Java applet plugin was removed from browsers in 2018. Fortunately, work done at St. Olaf College now makes it possible to convert (transpile) Java programs (both stand alone programs and applets) to JavaScript. Here we present examples of how this technology can be used to convert Java code generated by the Easy Java Simulations modeling and authoring tool.
The examples presented here were not recoded in JavaScript. The simulation's Java code is created using EJS and copied into the Eclipse Java development workspace where it is transpiled into JavaScript. In the end, the original functional of the Java program is virtually identical to its JavaScript counterpart, with all the layout, events, and functionality of the original.
The SwingJS transpiler developers maintain a <a href="https://github.com/BobHanson/java2script">GitHub repository </a> for Java developers who want to convert their Java applets or Java applications to JavaScript, allowing continued, simultaneous one-source development of both Java and JavaScript.Education Practices/Technology/Computershttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15444Wed, 12 Aug 2020 12:10:55 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15444Validating a Tracker-based Biomechanical Model
https://www.compadre.org/OSP/items/detail.cfm?ID=15439
A Tracker project and accompanying explanatory material showing an 8-segment Biomechanical model of the human body implemented in Tracker and compared to data derived from Vernier forces sensors.
The center of mass function in Tracker was used to compute the center of
mass of the model in each frame given the relative positions and masses of
the 8 segments. The protractor tool was used to derive knee flexion angle
data.Modern Physics/Biophysicshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15439Tue, 11 Aug 2020 11:50:16 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15439STP Chaos JS Simulation
https://www.compadre.org/OSP/items/detail.cfm?ID=15436
The Statistical and Thermal Physics (STP) JavaScript Chaos program is a ready-to-run computer model for the teaching of statistical and thermal physics. In this program we initialize 11 particles moving with the same velocity such that the net force on each particle is zero. The particles interact through a Lennard-Jones potential. Perturb the system very slightly and see what happens. The velocities can also be reversed to see to what extent the system is reversible.
The goal of this simulation is to explore how the smallest perturbation changes a special initial state of the system to one we would expect at thermal equilibrium. The idea of chaos or sensitivity to initial conditions is needed to understand why this happens, and to help explain irreversibility.
The STP Chaos program shown here was converted from Java to JavaScript by Wolfgang Christian and Robert Hanson (St. Olaf College) using the SwingJS system developed at St. Olaf College.Thermo & Stat Mech/Generalhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15436Sun, 26 Jul 2020 11:45:19 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15436Data Tool JS
https://www.compadre.org/OSP/items/detail.cfm?ID=15435
Data Tool is a data analysis tool for plotting and fitting data from laboratory experiments, simulations, video analysis, or any other data set organized into columns. Data Tool allows the user to plot multiple columns, control the appearance and scale of plots, view statistics, measure slope and area, manually or automatically fit built-in and user-defined functions to experimental data, and define new columns as functions of existing columns. See the Data Tool <a target="help" href="http://www.opensourcephysics.org/online_help/tools/datatool/datatool_help.html">online help</a> for additional information.
The Java implementation of the Data Tool program was written by Doug Brown at Cabrillo College using portions of the Open Source Physics code library developed by Wolfgang Christian at Davidson College. Data Tool was later converted from Java to JavaScript by Doug Brown, Wolfgang Christian and Robert Hanson using the <a href="https://chemapps.stolaf.edu/swingjs/site/swingjs/examples/about.html">SwingJS </a> system developed by Hanson and his students at St. Olaf College. This web page runs the JavaScript conversion.General Physics/Measurement/Unitshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15435Mon, 20 Jul 2020 15:13:51 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15435The constrained motion of a particle along a circular curve: Newtonian and Relativistic model
https://www.compadre.org/OSP/items/detail.cfm?ID=15357
In this work, we study, simulate and compare the constrained motion of a particle within two theoretical models: a relativistic and a Newtonian. The main objective is to get the user acquainted with the differences emerging in the treatment of the same mechanical system within the frames of Newtonian and the relativistic point of view. In the virtual environment of the simulation, the user can change the initial state of the moving particle and the gravity field within which it moves; so he can notice the resulting variations in the motion of the system.
To achieve the objectives we have set, the subsequent issues have been implemented: a) In the context of Newtonian Mechanics, determine and study a mechanical system consisted of a particle moving along a fixed curve of the three-dimensional Euclidean space, in the presence of a homogeneous gravitational field. In particular, we have considered the motion of a bead along a vertical circular wire. The same mechanical system is considered and studied in the context of the General Relativity. Hence we are in the position to compare the predictions obtained by the Newtonian and the relativistic model for the evolution of a well-known mechanical system. b) Simulate the motion of the particle according to the Newtonian and the relativistic model and compare their predictions in the virtual environment of the simulation. The simulation has been compiled in JavaScript language on the Easy JavaScript Simulations platform.Relativity/General Relativityhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15357Tue, 07 Jul 2020 08:59:15 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15357Diabolo Challenge at University of Oviedo
https://www.compadre.org/OSP/items/detail.cfm?ID=15426
The motion of a papercup diabolo glider is a classical example of the combined effect of Magnus Force, viscous friction and gravity. First year Math and Physics students at Universidad de Oviedo have recorded these videos of diabolo gliders and analyzed their trajectories with Tracker as a part of a class Challenge. Loops and cusps are observed at the initial stages of the glider motion. Then, the diabolo glider enters into a uniform rectilinear motion when Magnus and viscous forces cancel the effect of gravity. High speed videos also allow to characterize the glider rotation around its center of mass with constant angular speed.Classical Mechanics/Applications of Newton's Laws/Frictionhttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15426Tue, 07 Jul 2020 08:32:58 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15426Tracker/Excel/Python/Tracker Data Analysis
https://www.compadre.org/OSP/items/detail.cfm?ID=15430
Example of using Python to analyze digitized Tracker pixel data and return smoothed x and y point mass values that can be processed in Tracker to produce ripple free velocity and acceleration graphs.Classical Mechanics/Motion in Two Dimensionshttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15430Tue, 07 Jul 2020 08:05:35 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15430Teaching with Physlets
https://www.compadre.org/OSP/items/detail.cfm?ID=15366
Over the past 25 years, the Davidson College Physics Department has developed small computer programs called Physlets. These programs were written in Java and distributed as Java applets embedded in HTML pages. Physics teachers from around the world used Physlets to author interactive computer-based curricular materials for the teaching of introductory and advanced physics courses in multiple languages. Unfortunately, the Java plugin that enabled Java applets, including our original Physlets, to run was removed from browsers in 2018, Removing applet support, though critical for security reasons, was a major setback for physics education, since there had been thousands of applet-based HTML pages developed for physics and mathematics. To address this problem, we have converted Physlets to JavaScript so that they are compatible with all devices, inducing mobile platforms. This paper describes how these JavaScript Physlets can be used to improve teaching.Education Practices/Technology/Multimediahttps://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=15366Tue, 12 May 2020 13:37:15 ESThttps://www.compadre.org/OSP/items/detail.cfm?ID=15366