What can be changed:
• The sliders on either side change the vertical position of each ball
• mass(m) and initial horizontal velocity(vx) can be adjusted with slider bar
• Use mouse click and drag to change the position (click near the center of the ball) or the velocity vector (click near the arrow)
• check out the "paused when collide" checkbox to show more detail process during collision, Click mouse in the area to play it again

Physics processes:
1. when two ball meets, the program shows two components of the velocity for each ball (along the line connect two ball and perpendicular to it)
2. Interaction (force) between balls is along the line connect two balls
3. Velocitys perpendicular to connection line are not changed (No force/interaction in that direction)
4. The rest of the problem is similar to 1D collision problem for ball with velocity along the line

Virtual Physics laboratory Original URL

Fu-Kwun Hwang, Dept. Of Physics, National Taiwan Normal University.