Question

BMW car is travelling with a speed 252 kmph its brakes can produce maximum retardation 10 M per second square find the distance before it comes to rest and the distance travelled in the last second

Answer 1

252kmph in m/s=70m/s
using second equation of motion
${v}^{2} = {u}^{2} + 2as \\ {0}^{2} = 4900 - 2 \times 10 \times x \\ - 4900 = - 20x \\ so \: x = 245m$
using first equation of motion
$v = u \: + at \\ 0 = 70 - 10t \\ t = 7$
distance travelled in 7 seconds=252
distance travelled in six seconds=240m(using second equation of motion)
so distance travelled in last second=252-240=12m.
I HOPE IT WILL HELP YOU.