Question

A boulder rolls off a 100m high cliff at a speed of 5m/s. How long will it take for the boulder to hit the ground? How far from the base of the cliff will the boulder land?

Answer 1

$$t=\sqrt{2H/g}=\sqrt{2*100/9.8}=4.5\:\rm s$$

$$L=v_0t=5*4.5=23\:\rm m$$