Answer
22 m
Work Step by Step
Let down be the negative direction
$v^{2}=u^{2}+2ax$
$u=±\sqrt{ ((-27)^{2}-2(-9.8)(-15))}$
$u=-\sqrt{ (435)}$ since the gun was fired downwards
To find maximum height above the cliff edge:
$v^{2}=u^{2}+2ax$
$x=\frac{(0)^{2}-435}{2(-9.8)}\approx22 $ m
