Question

A model airplane is shot up from a platform 1 foot above the ground with an initial upward velocity of 56 feet per second.

Answer 1

$h=-16t^2+56t+1$

The ball will hit the ground when $h=0$:
$-16t^2+56t+1=0$
$D=b^2-4ac=56^2-4*(-16)*1=3136+64=3200$
$t=\frac{-b-\sqrt{D}}{2a}=\frac{-56-\sqrt{3200}}{-32}=\frac{-56-56.57}{-32}\approx 3.5$