Question

A body is dropped from the top of a tower. It acquires a velocity of $20m{s}^{-1}$ on reaching the ground. Calculate the height of the tower. (Take $g=10m{s}^{-2}$)

• A. $20m$
• B. $10m$
• C. $40m$
• D. $30m$

Answer 1

The correct option is A $20m$

Final velocity , $v=20m/s$
$g=10m/s^2$
By third eqation of motion we have,
$v^2=u^2+2gS$
Since, $u=0$
$S=\frac{v^2}{2g}$
$\Rightarrow S=\frac{{20}^2}{2\times 10}=20m$