Question

Your foot brake must be able to stop your car within __________ when it is travelling at 20 mph.

Answer 1

Answer:

Your foot brake must be able to stop car within 5.18 m

Explanation:

$d = s^{2} / (250 * c_{f} )$

d is breaking distance.

s is speed in km/h

$c_{f}$ is coefficient of friction normally 0.8

250 is  constant.

Give the speed in mile first convert it to km/h

$1 km = 1.60934 mile$

speed in km= 20 * 1.60934

s =32.186 km/h

$d=32.186^{2} / (250 * 0.8)$

d= 5.18m