Question

1. A rock is dropped from a height of 1.6 meters. How fast is the rock falling just before it hits the ground?

Answer 1

Given:

$h=1.6\:\rm m$

$g=9.8\:\rm m/s^2$

The law of conservation of energy says

$$mgh=\frac{mv^2}{2}$$

Hence, the final velocity

$$v=\sqrt{2gh}=\sqrt{2*9.8*1.6}=5.6\:\rm m/s$$