Question

A ball dropped from the top of a building strikes ground with a speed of 40 $m/s$. The height of building is approximately (neglect air resistance)

• A. 40 $m$
• B. $\sqrt{40}m$
• C. 80 $m$
• D. $\sqrt{80}m$

Answer 1

The correct option is C 80 $m$

$v=\sqrt{2gh}$
$h=\frac{v^2}{2g}=\frac{40\times 40}{20}=80m$