Question

A person driving a car with a speed 72km/hr suddenly sees a boy crossing road if the distance moved by car before the person applies brakes is 5 m the reaction time of person is

Answer 1

u= 72
v=0
s=5
t=?
v2-u2=2as
0-72*72=2*a*5
-5185=10a
a=-518.5

v=u+at
0=72+(-518.5)t
446.5=t ANSWER