Question

A boy on a bridge throws a stone horizontally with a speed of 25 𝑚/𝑠, releasing the stone from a point 19.6 𝑚 above the surface of the river. How far from a point directly below the boy will the stone strike the water? 

Answer 1

The time of falling:

$$t=\sqrt{2h/g}.$$

The horizontal distance:

$$R=vt=v\sqrt{2h/g}=50\text{ m}.$$