Question

on turning a corner a car driver driving at 36 km/h find a child on the road 55m ahead.he immediately apply break so as to stop within 5m of the child .calculate the retardation and time taken by the car to stop

Answer 1

just like this question
only you have to change the units to make it accurate if you found deceleration you will find time I hope this will help you

Answer 2

Given :

Initial velocity=u=36km/h=36x5/18=10m/s
Final velocity=V=0 m/s
acceleration=a=?
time =t=?
Distance travelled =S=55-5=50m
By using Third equation of motion,
V²-U²=2as
⇒0²-(10)²=2*a*50
a=-100/100
a=-1m/s²
V=U+at
0=10-1xt
-10=-1xt
t=10sec
=10 sec
∴ Acceleration is -1m/s² or retardation =1m/s²
time take by the car to stop=10sec