Question

You drop a rock from rest off a cliff, and it hits the ground 8.1 seconds later. How tall is the cliff？

Answer 1

The distance traveled by rock

$$s=v_it+\frac{gt^2}{2}$$

$$=0\times 8.1+\frac{9.8\times 8.1^2}{2}$$

$$=321\:\rm{m}$$