Question

When you see a traffic light turn red, you apply the brakes until you come to a stop. Your initial speed was 13 m/s. Assume constant deceleration. Suppose the car comes to rest in 38 m. How much time does it take?

Answer 1

Answer:

time is 5.85 sec

Explanation:

given data

speed u = 13 m/s

distance s = 38 m

to find out

How much time taken

solution

we know that formula for find time t

v = u + at   ............1

so first we find a

we will apply here formula to find a that is

v² - u² = 2×a×s    ............2

here we have given u and s and we know v = 0

so we find here a

0² - 13² = 2×a×38

-169 = 76 a

a = - 2.223

so from equation 1

0 = 13 - 2.223 × t  

t = 13 / 2.223 = 5.85

time is 5.85 sec