Height of a cliff?

Question

When a rock is dropped from a cliff into an ocean, it travels approximately 16t^2 feet in t seconds. If the splash is heard 4 seconds later and the speed of sound is 1100 ft/s, approximate the height of the cliff.

Thanks.....

Answer 1

x = 16t^2
x = vt

let t represents the time the rock hit the ocean. The total time is 4sec, that means the time for sound to reach you is 4-t

since the distance is the same, we have

16t^2=1100(4-t)
16t^2= 4400-1100t
16t^2+1100t-4400

use quadratic fomula and you'll get t=3.79096s

16(3.79096)^2=229.94ft

Answer 2

Approximately 230 feet