Ejs Open Source Horizontal Circular Motion of Mass on a table java applet
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1454.0

this 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}
[b][color=blue]You should change radius only for perfect circular motion,[/color][/b] changing M or m will result additional radial acceleration which then the motion is not [b][color=red]circular[/color][/b] 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!

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