Question

The driver of a car traveling down the interstate slams on the brakes, causing the car to skid to rest over a distance of 119.7 m. If the car experienced an acceleration of -10.94 m/s2 during this time, how long did it take for the car to come to rest?

Answer 1

Given:

The distance covered by the car after the driver applies the brake, d=119.7 m

The acceleration of the car, a=-10.94 m/s²

The final velocity of the car, v=0 m/s

To find:

The time it takes for the car to come to stop.

Explanation:

From the equation of motion,

$d=vt-\frac{1}{2}at^2$

On substituting the known values,

$\begin{gathered} 119.7=0-\frac{1}{2}\times-10.94\times t^2 \\ t=\sqrt{\frac{119.7\times2}{10.94}} \\ =4.7\text{ s} \end{gathered}$

Final answer:

Thus the car comes to rest in 4.7 s