What is the speed of a rock if you drop it from a tall bridge
v = g t
at distance d below bridge:
d = (1/2) g t^2
so
t = sqrt (2 d/g)
and
v = g sqrt (2 d/g) = sqrt (2 g d)
at distance d below bridge:
d = (1/2) g t^2
so
t = sqrt (2 d/g)
and
v = g sqrt (2 d/g) = sqrt (2 g d)