Water flows through the convergent/divergent channel at 0.06 kg/s. calculate the ideal head in mm at the piezo tube where the cross sectional area of the channel is 90 mm2. assume the density of water is 1000 kg/m3

here you go :)

Explanation:

I was thinking southwest was in 3 dimensions. But i guess it is in 2 dimensions in the plane. So like the user below said, it wont have an effect on the time it takes to reach the ground. Initial velocity of rock is zero, and solving 0 = -1/2 * 9.8 * t^2 + 78,  gives me t = 3.9897828696  or about  t= 4.0 seconds