Question

A driver is traveling 18.0 m/s when she sees a red light ahead. Her car is capable of decelerating at a rate of 3.40 m/s...


A driver is traveling 18.0 m/s when she sees a red light ahead. Her car is capable of decelerating at a rate of 3.40 m/s^2

A.) If it takes her 0.420 s to get the brakes on and she is 20.0 m from the intersection when she sees the light, will she be able to stop in time?

Answer: No

B.)How far from the beginning of the intersection will she be?
I know the answer is not 47.64 or 10.21. Please HELP solve for B!
 
 
 

Answer

(A)

The distance travelled by car before she applies the break is:

Physics homework question answer, step 1, image 1

From kinematics, the expression for the final velocity is:

Physics homework question answer, step 2, image 1

Therefore, the total distance covered by the car before it stops is:

Physics homework question answer, step 2, image 2

Since the car travels 55.21 m before it stops. Thus, the driver is not able to stop the car in time.

Therefore, no will be the answer.

(B)

The position of the car from the beginning of the intersection will be:

Physics homework question answer, step 3, image 1

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