according to the 3rd motion equation
vf^2=vi^2+2ad
since it has moved from rest ..therefore vi=0
vf^2=2×2.3×55=253 m/s
so vf=sqr(253) m/s
.....
to get tge time...according to motion 1st equation vf=vi+ at
vi=0
therefore ,
vf=at
sqr(253)=2.3t
t=sqr(253)/2.3
=6.9 sec.
.......................
or, to get the time according to motion 2nd equation
d=vit+1/2 at^2
vi=0
d=1/2at^2
55=1/2×2.3t^2
t^2=47.8
t=sqr(47.8)
t=6.9sec.
