Question

Felipe drives his car at a velocity of 28 m/s. He applies the break, which slows the vehicle down at a rate of 6.4 m/s ^2 and causes it to slow to a stop. How long does it take for the car to stop?

Answer 1

If the acceleration applied is constant, then it is the same as the average acceleration throughout the duration of the stop.

$a=\dfrac{\Delta v}{\Delta t}\implies-6.4\,\dfrac{\mathrm m}{\mathrm s^2}=\dfrac{0-28\,\frac{\mathrm m}{\mathrm s}}{\Delta t}\implies\Delta t=4.4\,\mathrm s$