Question

Jocelyn is driving a 1375kg car at 18.0m/s. When someone steps out infront of her she, she slams on the brakes and she comes to a stop due to the 16,000N braking force. calculate how long she took to bring the car to a stop.

Answer 1

In order to calculate how long does it take to stop the car, first let's calculate the car acceleration, using the second law of Newton:

$\begin{gathered} F=m\cdot a\\ \\ -16000=1375\operatorname{\cdot}a\\ \\ a=\frac{-16000}{1375}\\ \\ a=-11.636\text{ m/s^^b2} \end{gathered}$

Now, we can use the formula below for the velocity with constant acceleration:

$\begin{gathered} V_f=V_i+a\operatorname{\cdot}t\\ \\ 0=18-11.636\operatorname{\cdot}t\\ \\ 11.636t=18\\ \\ t=\frac{18}{11.636}\\ \\ t=1.55\text{ s} \end{gathered}$

Therefore it will take 1.55 seconds for the car to stop.