Question

A depth of 10m of water exerts the same amount of pressure as the entire Earth's atmosphere which is~120km thick.Suggest why

Answer 1

Given:

$h_{\rm water}=10\:\rm m$

$\rho_{\rm water}=1000\:\rm kg/m^3$

$h_{\rm air}=120\:000\:\rm m$

$\rho_{\rm air}=0.0833\:\rm kg/m^3\; (mean\; density)$

The hydrostatic pressure is given by

$$p=\rho g h$$

We get

$$p_{\rm water}=1000*9.8*10=98\: 000\:\rm Pa$$

$$p_{\rm air}=0.0833*9.8*120\:000=98\: 000\:\rm Pa$$