a)
s = 1/2·g·t^2
t = √(2·s/g) = √(2·(1500 m)/(9.81 m/s^2)) = 17.49 s
b)
vX = 500 km/h = 138.9 m/s
vY = g·t = (9.81 m/s^2)·(17.49 s) = 171.6 m/s
vG = √((138.9 m/s)^2 + (171.6 m/s)^2) = 220.8 m/s = 794.8 km/h
c)
s = v·t = (138.9 m/s)·(17.49 s) = 2429 m