# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## Easy Java Simulations (2001- ) => Collaborative Community of EJS => Topic started by: lookang on July 04, 2010, 08:24:26 pm

 Title: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: lookang on July 04, 2010, 08:24:26 pm Ejs Open Source Horizontal Circular Motion of Mass on a table java applethttp://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1454.0this applet is customized to allow visualization & sense making of circular motion of the case of Horizontal Circular Motion of Mass on a table.Conservation of Angular momentum and 3D circular motion  A particle with mass m is moving with constant speed v along a circular orbit (radius r).gravitational force Mg from another mass M hanging from the string, provides the centripetal acceleration for horizontal circular motion of mass m.A string is connected from mass m to the origin ( a hole for the string to pass in through) then connected to mass M.This model assume conservation of angular momentum $\vec{L}=m\,\vec{r}\times \vec{v}$ . i.e. $L=mr^2\omega$ is a constant.For particle with mass m: $m \frac{d^2r}{dt^2}= m \frac{v^2}{r}-Mg=\frac{L^2}{mr^3}- Mg$ $\omega=\frac{L}{mr^2}$You should change radius only for perfect circular motion, changing M or m will result additional radial acceleration which then the motion is not circular but elliptical.I would like to thank Prof Hwang Fu-Kwun for his superb guidance and masterful support that facilitated my self directed informal learning and collaborate with world-class physicists to make customize applets for the general well being of the world. And Prof Paco for creating easy java simulation! and 3D java rocks! but there are some bugs (can toggle to Java3D to test, it will hang) :) await for improved releases of Ejs4.3.0! Title: Re: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: lookang on July 04, 2010, 08:25:22 pm changes made:1 added text into the source codes2 verified the physics of CO angular Momentum in the codes3 added contact force N, weight mg and tension T4 added Java 3D5 added angular displacement theta, angular velocity omega, time t, centripetal acceleration a6 added tangential velocity v and radial velocity vr7 change some color scheme8 add some slider and bars to show values9 design all variables to be drawn in 3D with checkboxes for sense making10 decode the Conservation of Angular momentum and 3D circular motion with my T1 = m*v*v/r + m*dvr/dt ? // radial acceleration due to tangential change in velocity and radial acceleration due to radial change in velocity ? where dvr/dt = (cst*cst/(m*r*r*r)-M*g)/m11 too tired to write compare http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1454.0 with this post to know changes made by me :)12 changed back to simple 3D default because Java 3D still improving.13 change the table to current color scheme for faster rendering Title: Re: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: Fu-Kwun Hwang on July 07, 2010, 09:51:00 pm Java 3D look nice. However, most of the users might not be able to see it.I can not see it on web version,too!May be you can have two versions, one without java3D ,and add another downloadable jar file for java3D. Title: Re: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: lookang on July 07, 2010, 10:44:39 pm java.lang.NullPointerException   at users.sgeducation.lookang.circular3dfr02_pkg.circular3dfr02View.reset(circular3dfr02View.java:1560)   at org.colos.ejs.library.Animation.reset(Unknown Source)   at users.sgeducation.lookang.circular3dfr02_pkg.circular3dfr02Simulation.(circular3dfr02Simulation.java:25)   at users.sgeducation.lookang.circular3dfr02_pkg.circular3dfr02.(circular3dfr02.java:93)   at users.sgeducation.lookang.circular3dfr02_pkg.circular3dfr02Applet.init(circular3dfr02Applet.java:27)   at sun.applet.AppletPanel.run(AppletPanel.java:424)   at jep.AppletFramePanel.run(Unknown Source)   at java.lang.Thread.run(Thread.java:637)same on the Mac.will make default simple 3DYouTube. Was stuck at Portland airport from 11pm to 4am, decided to use the time to make some promotional video on the applets shared during 2010 AAPT Summer Meeting in Portland, Oregon Title: Re: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: ahmedelshfie on July 07, 2010, 11:24:21 pm Nice java 3d look beautiful,, i test by HTML and work very well.Any way i like version java 3D good job  :D Title: Re: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: lookang on July 08, 2010, 08:30:48 am Quote from: ahmedelshfie on July 07, 2010, 11:24:21 pmNice java 3d look beautiful,, i test by HTML and work very well.Any way i like version java 3D good job  :Di like java 3D too, but just be aware, it may fail for complex simulations.the above applet get stuck sometimes in java3D mode.  >:( Title: Re: Ejs Open Source Horizontal Circular Motion of Mass on a table java applet Post by: lookang on July 12, 2010, 12:42:04 pm 09 July 2010 Computer Lab hands on learning session on  Ejs Open Source Vertical Circular Motion of mass m attached to a rod java applet 3D view with teacher demo and student working on their own desktop09 July 2010 Computer Lab hands on learning session on  Ejs Open Source Vertical Circular Motion of mass m attached to a rod java applet 3D view with teacher explaining and student working on their own desktop09 July 2010 Computer Lab hands on learning session on  Ejs Open Source Vertical Circular Motion of mass m attached to a rod java applet side view of the same 3D view with teacher explaining the physical setup of the mass m and mass M attached by a string through a table with a fricitionless hole in the middle of table for string to go through and student working on their own desktophttp://sgeducation.blogspot.com/2010/07/lesson-on-circular-motion-with-acjc.html