Question

A body is initially at rest . it undergoes one dimensional motion with a constant acceleration .how does its displacement"s" depend on time"t"?

Answer 1

use 2nd eq. of motion
s = ut+(1/2)at^2

u = 0
so it becomes,
s =(1/2)at^2

exchange sides and you'll get
a =(2s)/(t^2)

Answer 2

use seconed equation of motion
s=ut+1/2at^2

then , initial vel becomes 0so s=1/2 at^2