The relation for elastic 1D collision become very simple if viewed from center of mass reference frame.

Before collision: two particles with mass and velocity as m_1,\vec{v_1} and m_2,\vec{v_1}
After collision: the velocity have been changed to \vec{v_1}' and \vec{v_2}'

The center of mass X_{cm}= \frac{(m_1*x1+m2*x2)}{(m_1+m_2)}
\vec{V}_{cm}= \frac{(m_1*\vec{V_1}+m2*\vec{V_2})}{(m_1+m_2)}

\vec{V_1}'-\vec{V}_{cm}=\vec{V}_{cm}-\vec{V}_1=-(\vec{V}_1-\vec{V}_{cm})

\vec{V_2}'-\vec{V}_{cm}=\vec{V}_{cm}-\vec{V}_2=-(\vec{V}_2-\vec{V}_{cm})

translate strings in simulation to different language format before download
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1129.3kB):double click downloaded file to run it. (4 times by 4 users) , Download EJS source View EJS source