Question

an aeroplane needs a velocity of 360 km per hour for the take off. If it starts from rest and accelerates at the rate of 4 m per second^2 what must be the minimum length of the runway

Answer 1

by using third eq. of motion we can do this 
v^2-u^2=2as
v=360km/h=360*5/18=100m/s
u=0
then
100^2-0^2=2*4*s
10000-0=8s
10000/8=s
1250m=s