The minimum stopping distance of a car moving at 20.5 mi/h is 11.6 m. Under the same conditions (so that the maximum braking force is the same), what is the minimum stopping distance for 50.2 mi/h?

d = 69.57 meter

Explanation:

First case

Speed of car (v) = 20.5 mi/h = 9.164 M/S

distance (d) = 11.6 meter (m = mass of the car)

Work done = 0.5 m v² = 0.5 * 9.164² * m J = 41.99 m J

Force = (workdone / distance) = (41.99 m / 11.6) = 3.619 m N

Second case

v = 50.2 mi/h = 22.44135 m/s

d = ?

Work done = 0.5 * 22.44² * m J = 251.7768 * m J

Since the braking force remains the same.

3.619 m = (251.7768 m / d)

d = 69.57 meter