Question

A rock is dropped from a cliff and hits the ground 6.0 seconds later. How high is the cliff?

Answer 1

Use
h=ut+.5gt^2

Answer 2

Hint:
the relationship between the height and the time, is:
\[h = \frac{1}{2}g{t^2}\]
where g is the gravity, namely g=9.81 m/sec^2. So substituting your data into the equation above, we get:
\[h = \frac{1}{2}g{t^2} = \frac{1}{2} \times 9.81 \times 36 = ...?\]