posted by steph .
A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of vi = 11 m/s. The cliff is h = 47 m above the water's surface, as shown below.
You gave the details but failed to ask the question.
If you want to know how far away from the (vertical) cliff the stone hits the water, multiply 11 m/s by the time T that it takes the stone to fall to the water's surface.
(g/2)T^2 = 47 m
T = sqrt (2*47/9.8)= 3.1 s