Question

A stone is dropped into a well and 4 seconds later the sound of the splash is heard. If sounds travel at a speed of 340 m/s, how deep is the well ?

Answer 1

Given:

$t=4\:\rm s$

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

$u=340\:\rm m/s$

The time between you dropped a stone and you heard the sound of splash

$$t=t_1+t_2=\sqrt{2h/g}+h/u$$ $$4=\sqrt{2h/9.8}+h/340$$

The root of this equation

$$h=70.5\:\rm m$$