Car b is traveling a distance d ahead of car a. both cars are traveling at 60 ft> s when the driver of b suddenly applies the brakes, causing his car to decelerate at 12 ft> s2. it takes the driver of car a 0.75 s to react (this is the normal reaction time for drivers). when he applies his brakes, he decelerates at 15 ft> s2. determine the minimum distance d be tween the cars so as to avoid a collision.