Question

when brakes are applied to a car running on a straight road retardation of 4m?/s is produced. if stops after 3s calculate the distance travelled after brakes are applied

Answer 1

$s = u t + \frac{1}{2} a {t}^{2}$

Answer 2

a= -4m/s^2

t=3s

v=0m/s

according first equation of motion

v=u+at

0=u+(-4)×3

0=u-12

u=12m/s

according third equation of motion

v^2=u^2+2as

0^2=12^2+2×(-4)×s

0=144-8s

8s=144

s=144÷8

s=18m