It takes 100 m to stop a car initially moving at 25.0 m/s. The distance required to stop the same car moving at 50.0 m/s under the same conditions is
A) 25.0 m.
B) 50.0 m.
C) 100 m.
D) 200 m.
E) 400 m.

Question

Quizplus · Accepted Answer

The stopping distance is proportional to the square of the speed. Doubling the speed from 25.0 m/s to 50.0 m/s increases the stopping distance by a factor of four (since (50/25)^2 = 4), so the distance required is 400 m.

It Takes 100 M to Stop a Car Initially Moving