This problem demonstrates what would happen if your lungs were not coated with lung

surfactant. Aveoli, the small air sacs in your lungs, can be thought of as a background of

liquid containing a foam of connected bubbles. Imagine two connected aveoli of radius $0\mathrm{.}1$

mm and $0\mathrm{.}5$ mm$.$ If the surface tension of the aveoli were the same as at an air$-$water interface

$(7+103$N$/$m$),$

$($a$)$ Calculate the difference in surface$-$tension induced pressure $($Laplace pressure$)$ between

the $0.1$ mm radius aveoli and the $0\mathrm{.}5$ mm radius aveoli.

$($b$)$ Surface tension effects are most easily seen for small bubbles or droplets. A typical

surface tension is on the order of $3*102$ N$/$m$.$ What is a typical length radius at which the

Laplace pressure is about equal to atmospheric pressures?