Problem 12.17 Car B is traveling a distance d ahead of car A, Both cars are trav
ID: 1405685 • Letter: P
Question
Problem 12.17 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/s2It takes the driver of car A 0.75s to react (this is the normal reaction time for drivers). When he applies his brakes, he decelerates at 19 ft/s2 Copy Define termine the minimum distance d between the cars so as to avoid a collision. Express your answer to three significant figures and include the appropriate units.
Explanation / Answer
Distance between two cars = d ft
Initial Speed = 60ft/s
Distamce travelled by car B in 0.75 s =
S = 60 * 0.75 - 0.5 * 12 * 0.75^2 = 41.625 ft
Distance travelled by Driver A in reaction time = 0.75s *60 ft/s = 45ft
Minimum distance d between the cars should be = 45-41.625
Minimum distance d between the cars should be = 3.375 ft