A ball is kicked off a flat roof with a horizontal velocity of 12ms-1

How would you:
a. Calculate the horizontal distance traveled after it has fallen 15m?
B. Calculate the resultant velocity after 1.9s?

Time to fall 15m. = sqrt. (2h/g), = 1.7496 secs.
a) It is (1.7496 x 12) = 20.996m. from the roof.
b) Vertical component = (gt) = 9.8 x 1.9, = 18.62m/sec. Horizontal component = 12m/sec.
velocity = sqrt. (18.62^2 + 12^2) = 22.152m/sec., and direction = atn. (12/18.62) = 32.8 deg. from vertical.

i assume the use of g = 9.81 m/s^2, but i also included answers for g = 10 m/s^2
a)
the vertical distance traveled due to the force of gravity is (1/2)*g*t^2
equate this to the height
1/2 * g * t^2 = 15
t^2 = 30/g
t = sqrt(30/g)
t = 1.75 (1.73 if g = 10)

b)
the vertical increase in velocity due to the force of gravity is gt
v_y = gt
v_y = 18.6 (19 if g = 10)

v^2 = v_x^2 + v_y^2
v^2 = 22.1 (22.5 if g = 10)