See link: http://www3.interscience.wiley.com:8100/legacy/college/cutnell/0471713988/ste/ste.pdf. When defining surface tension, the article makes reference to a C-shaped apparatus. Why is γ = F/2l and not F/l? It says something about there being two surfaces, but it seems to me that because there's only one surface touching the wire, it should be F/l. Second question: In example one, surface tension is applying a force outwards on the needle. But based on the introductory explanation of surface tension, I thought surface tension was only inwards. I can see why compressing the liquid will produce some outward force against the needle, but why would that equal γL? It seems like those are two different phenomena. I am obviously well aware that I probably have a deep missunderstanding of what's actually going on. The way I see it, any molecule on the surface will be 'sucked' in, and that's the force which is pulling the wire in in the first question. Is this at all correct? Thanks a lot!