Question

A ball is released from a height and it reaches the ground in $3s$. If $g=9.8m{s}^{-2}$, find height

Answer 1

Given,

$u=0m/s$

$t=3sec$

$g=9.8m/s^2$

From 1st equation of motion,

$v=u+gt$

$v=0+9.8\times 3$

$v=29.4m/s$

From 3rd equation of motion,

$2gh=v^2-u^2$

$h=\frac{v^2-u^2}{2g}$

$h=\frac{29.4\times 29.4-0^2}{2\times 9.8}$

$h=44.1m$

Height is $44.1m$.