# Surface Tension problem

1. Dec 12, 2014

### Aias

1. The problem statement, all variables and given/known data
http://ocw.mit.edu/courses/mechanic...cs-spring-2013/assignments/MIT2_06S13_ps2.pdf
Problem 7

2. Relevant equations
$F=2*V/(a^2)*\sigma*cos(180-\theta)$

3. The attempt at a solution
With the problem statement given, it seems like the component of surface tension in the vertical direction on the upper plate would be in the same direction as the proposed required force due to the surface being non-wetting, thus no need for an actual force F to hold the plates together. I don't see what kind of force would want to push the plates apart? I came to that equation after some fiddling around, it seems like it could be correct, but I don't have an intuitive understanding why it would be so.

2. Dec 12, 2014

### Staff: Mentor

As a result of the surface tension effect, is the pressure in the liquid between the plates higher of lower than the pressure of the surrounding atmosphere?

Chet