You are driving just behind a second car and both of you are moving at a speed 6

Question

You are driving just behind a second car and both of you are moving at a speed 62 mi/h . If the car in front of you suddenly slams on her brakes, you will apply your breaks as quickly as you can. This time is called your reaction time and is typically 200 ms. Assume both cars accelerate at the same rate of - 7.00 m/s2 .

What is the closest distance your front bumper can be behind the rear bumper of the car in front of you and not crash into her car?

If you are very tired after a long night, or you are texting, or you are alcohol impaired, your reaction time can be twice your standard reaction time. What is the minimum safe distance now?

Explanation / Answer

speed of travel of each car = 62 mi/h = 62 x 0.45 m/s = 28 m/s

let the distance between the car = d

for the front car :

Vi = initial velocity = 28 m/s

acceleration = a = - 7 m/s2

final velocity = Vf =0

distance travelled by the front car before coming to stop is given as

D = (Vf2 - Vi2 )/ (2a) = (02 - 282 ) / (2 x -7) = 56 m

for second car ::

distance travelled in response time :

d1 = 28 x 0.2 = 5.6 m

distance travelled to come to stop = d2 = 56 m

so distance between cars = 5.6 m

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.