Neglecting reaction time, the distance required for a car to stop is directly proportional to the square of...

Question

Neglecting reaction time, the distance required for a car to stop is directly proportional to the square of its velocity. If a car can stop in 8.5 meters at 20 kilometers per hour, how many meters are needed to stop at 40 kilometers per hour?

34

40

.85

1882.35

Answer 1

Since 40 is twice 20, 40 squared is four times 20 squared. Since the square of the speed went up by a factor of four, so will the stopping distance. So 34 meters (8.5 * 4).