Answer:
H = 1/2 * g * t^2 since initial velocity is zero
v = g * t where v is the final velocity
t = v / g
H = 1/2 g * v^2 / g^2 = 1/2 v^2 / g
v = (2 * H * g)^1.2
v = (2 * 500 * 9.8)^1/2 = 99 m/s
Check: t = v / g = 99 / 9.8 = 10.1 sec
H = 1/2 * 9.8 * 10.1^2 = 500 m