Knowing that the position function of a free-falling object is represented by the equation s(t)=(1/2)gt2+v0t+s0 where
g=acceleration due to gravity, which is approximately -32ft/sec2
v0=initial velocity of the object. In our case v0=0
s0=initial height of the object. In our case s0=350ft
We want to solve for t when s(t)=0:
Because time cannot be negative, the answer is approximately 4.68 seconds.