You are driver. Select applet with mouse.
Your speed will grow up, if you press M
Your speed will go down, if you press N
Bus in front of you breaks in random time.
Bottom of applet are graph.
If after bus break will be crash, then red dot appears in graph.
If after bus break you stopped correctly, then appear black circle in graph.
So you can find experimental model for relationship between speed and distance between vehicles.