Question

A driver is traveling 18.4 m/s when she sees a red light ahead. Her car is capable of decelerating at a rate of 3.65 m/s^2 .

If it takes her 0.370 s to get the brakes on and she is 20.0 m from the intersection when she sees the light.

How far from the beginning of the intersection will she be?

Answer 1

Answer:

33.19 meters

Explanation:

First let's calculate the initail distance

S1 = 18.4 x 0.370 = 6.808 meters       (Using, speed = distance/time)

Now, let's calculate the distance traveled during deaaceleration,

(here final speed will be zero and initial speed will be 18.4 m/s^2)

Using, V^2 = U^2 + 2 S a

0 = (18.4)^2 + 2 S (-3.65)

S = (18.4)^2 / (2 x 3.65)

S = 338.56 / 7.3

S = 46.38 meters

Now, the total distance traveled is,

6.808 + 46.38 = 53.19 meters                   (S1 + S)

So, the distance from the beginning of the intersection will be,

53.19-20 = 33.19 meters