difference in distance S= 30m-12m=18m.
initial velocity u=0, distance S=1/2at^2 at
a=2S/t^2=2×18/25=36/25=1.44m/s^2..having gotten the acceleration...we can get the velocity
using V^2=U^2+2aS . since u=0
v^2= 2×1.44×18=51.84
V=sqroot51.84
V=7.2m/s( that is the velocity)
