A ball is thrown horizontally from a cliff and hits the ground 4 seconds later 40 meters from the base of the cliff. How high was the cliff (rounded to the nearest tenth of a meter)?

Answer 1

height h is given by

h = h0 - 4.9t^2
so, to find h0, set h=0

0 = h0 - 4.9(16)
h0 = 78.4m

the horizontal distance is irrelevant to finding the cliff height

Answer 2

78.4