A teen was driving home. He hit the breaks, skidding to a stop. Being a student in forensics science, he noticed that his car had left skid marks. He measured them: 14 feet. Only two of his front tires and one back tire left a mark. He estimates, the drag value of the road is around 0.5. He goes home, to calculate how fast he was going when he hit the breaks for the turtle.
S = square root of 30 x 14 x 0.5 x n