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32 votes
32 votes
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.

User Tam Huynh
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1 Answer

20 votes
20 votes

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=(-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=(18)/(11.636)\\ \\ t=1.55\text{ s} \end{gathered}

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

User Jan Petr
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