An inattentive driver is traveling 15.0 m/s when he notices a red light ahead. his car is capable of decelerating at a rate of 3.35 m/s2. part a if it takes him 0.210 s to get the brakes on and he is 66.0 m from the intersection when he sees the light, will he be able to stop in time

Question

Margaret Braun

Physics

19 October, 07:59

An inattentive driver is traveling 15.0 m/s when he notices a red light ahead. his car is capable of decelerating at a rate of 3.35 m/s2. part a if it takes him 0.210 s to get the brakes on and he is 66.0 m from the intersection when he sees the light, will he be able to stop in time

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Answers (1)

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Erica Le · Answer 1

We know that v = u + at

He stops when the speed is zero; therefore

0 = 15 - 3.35 t

t = 4.48

It takes 4.48 seconds after the driver turns on the brake for him to stop.

We know

s = ut + (1/2) at ²

s = 15*4.48 - * (1/2) (3.25) (4.48) ²

s = 33.4 meters

The distance he travels before applying the brakes is:

s = 0.21 * 15

s = 3.15 m

The total distance he travels is:

3.15 + 33.4 = 36.55 meters

He will be able to stop in time.