Question

A car is traveling at 13.0 m/s, and the driver sees a traffic light turn red. After 0.590 s (the reaction time), the driver applies the brakes, and the car decelerates at 8.00 m/s2. What is the stopping distance of the car, as measured from the point where the driver first sees the red light?

Answer 1

Gien

car traveling at 13.0 m/s and driver applied the brakes after 0.59 s so

the displacement covered in 0.59 s is  

s1 = 0.59*13 m = 7.67 m

and

after applying the brakes car decelerating with 8 m/s2 after some time comes to rest by covering a distance of s2

the distance covered before come to rest is  

using equations of motion

v^2 - u^2 = 2*as

finally car comes to rest so t v = 0

u = 13 m/s

a = -8 m/s2

0-13^2 = 2*8*s2

solving for s2 , s2 = 10. 5625 m

the total distance covered by the car before come to rest is  

S = s1+s2 = 7.67+10.5625 m = 18.2325 m