A car is being driven at a rate of 40 ft/sec when the brakes are applied. The car decelerates at a constant rate of 11 ft/sec2. How long before the car stops? Round your answer to one decimal place.

Respuesta :

Answer:

The distance the have traveled before come into the rest = 72.72 ft

Step-by-step explanation:

Velocity of the car u = 40 [tex]\frac{ft}{sec}[/tex]

Final velocity of the car V = 0

Acceleration of the car a = - 11 [tex]\frac{ft}{sec^{2} }[/tex]

First equation of motion,

V = u - at --------- (1)

Put all the values in equation 1, we get

0 = 40 - 11 t

⇒  t = [tex]\frac{40}{11}[/tex] = 3.636 [tex]\frac{ft}{sec^{2} }[/tex]

Now the distance traveled by the car before come into rest  

[tex]S = u t + \frac{1}{2} a t^{2}[/tex]

Put all the values in the above equation we get,

S = 40 × 3.636  - [tex]\frac{1}{2}[/tex] × 11 × [tex]3.636^{2}[/tex]

S = 145.44 - 72.71

S = 72.72 ft

This is the distance the have traveled before come into the rest.