# Problem on Pressure due to Surface tension

phantomvommand
Homework Statement:
Relevant Equations:
##\gamma = \frac F L##
##P = \frac F A## The method to solving this is to equate forces along a portion of the balloon through which ##\sigma_L## acts, and another portion through which ##\sigma_t## acts. The former potion should be a circular cross section of the cylinder, while the latter will be a rectangular cross section. You will thus get the following: I did exactly the above, except that instead of having ##2\pi r \sigma_L## and ##2x\sigma_t## on the RHS, I had ##4\pi r \sigma_L## and ##4x\sigma_t##. Am I right on this? Because I think that in either case, there are 2 surfaces (inner surface of balloon and outer surface of balloon), resulting in double the force exerted by surface tension.

Here it doesn't really matter how you define ##\sigma_L## and ##\sigma_t## just so long as you're consistent because at the end you're taking a ratio. So I wouldn't worry about it too much! • 