can be used to approximate the speed S, in miles per hour, of a car that has left skid marks of length D, in feet. To determine how far a car will skid at 70 mph, we will substitute 70 mph for S in the formula. It becomes
70 = 7/2√2D
We will take squares of both sides. This is to simplify the square root on the right had side of the equation. It becomes
