The stopping distance (s) of a car varies directly as the square of its speed (v). If a car traveling at 30 mph requires 59.85 ft to stop, find the stopping distance for a car traveling at 55 mph.
A) 32.645 ft
B) 81.037 ft
C) 17.807 ft
D) 109.725 ft
E) 201.163 ft

Question

Quizplus · Accepted Answer

The stopping distance varies directly with the square of the speed, so s = k * v^2. First, find k using 59.85 = k * 30^2, which gives k = 59.85 / 900. Then, use this k to find the stopping distance for 55 mph: s = k * 55^2, which results in approximately 201.163 ft.

The Stopping Distance (S) of a Car Varies Directly as the Square