Question

In many locations, old abandoned stone quarries have become filled with water once excavating has been completed. While standing on a quarry wall, a boy tosses a piece of granite into the water below. If he throws the rock horizontally with a velocity of 3.0 m/s and it strikes the water 4.5 m from the base of the wall, how high above the water is the wall?

Alright I think figured out that time = 1.5s
because D = VT
4.5m = 3.0 m/s * T
but where do I go from here?

Answer 1

Dh = Vt,
T = Dh/V = 4.5/3 = 1.5s. = Time in flight = Fall time.

h = Vo*t + 0.5g*t^2,
h = 0 + 4.9(1.5)^2 = 11.03m.

Answer 2

s=vt
4.5=3t
t=1.5

s=0.5(-10)1.5^2
=-5(1.5)^2
=-11.25 m
The wall is 11.25 m above the water (the answer is negative because the granite falls in a negative direction)