Question

What is the pressure (in N/m2) inside an alveolus having a radius of 2.22 ✕ 10−4 m if the surface tension of the fluid-lined wall is the same as for soapy water? You may assume the pressure is the same as created by a spherical bubble.

Answer 1

The pressure inside the bubble is 666.67
`N/m^(2)`

Solution:

As per the question:

Radius, R =
`2.22* 10^(- 4)\ m`

Now,

Given that the surface tension of the wall is the same as that of soapy water.

The air trapped inside the bubble exerts pressure on the soap bubble which is given by:

Gauge Pressure, P =
`(4T)/(r)`

Also, the surface tension of the soapy water,
`T_(s) = 0.0370\ N/m^(2)`

To calculate the pressure inside the alveolus:

`P_(i) = (4T)/(R) = (4T_(s))/(R)`

`P_(i) = (4* 0.0370)/(2.22* 10^(- 4)) = 666.67\ N/m^(2)`