The minimum distance required to stop a car moving at 35.6 mi/h is 40.8 ft. What is the minimum stopping distance, in ft, for the same car moving at 71.5 mi/h, assuming the same rate of acceleration? (60.0 mi/h = 88.0 ft/s).

Minimum stopping distance = 164.69 ft

Explanation:

Speed of car = 35.6 mi/hr = 15.82 m/s

Stopping distance = 40.8 ft = 12.44 m

We have equation of motion

v² = u² + 2as

0²=15.82² + 2 x a x 12.44

a = - 10.06 m/s²

Now wee need to find minimum stopping distance, in ft, for the same car moving at 71.5 mi/h.

Speed of car = 71.5 mi/h = 31.78 m/s

We have

v² = u² + 2as

0² = 31.78² - 2 x 10.06 x s

s = 50.2 m = 164.69 ft

Minimum stopping distance = 164.69 ft