Question

A stone is dropped from the top of a cliff. The splash it makes when striking the water below is heard 6.9 s later. How high is the cliff?

Answer 1

This is provided it starts from rest:
t=6.9 u=0 a=-9.8 (acceleration due to gravity) s=?

S=ut+0.5at^2
S=0+0.5(-9.8)(6.9^2)
S=(-4.9)(47.61)
s=-233.289m (minus is because it’s below starting point)
s=233.289metres