Relative Speed Calculator...
Consider two cars travelling side by side on a straight level surface. One is going faster than the other. They both do an emergency stop when they are exactly side by side. This calculator will work out the speed at which the faster car is travelling when it reaches the point at which the slower one stopped and the distance it will travel before it too has stopped.
Enter the speed of the faster car in the top box, the speed of
the slower in the middle box, then click on Calculate. The results
will be shown in the bottom boxes.