Science Buddies: "Ask an Expert"

In my experiment, surface tension is defined as: F=2sd, where
F is force in newtons to pull an object (in this case a pin) from the surface of a liquid,
s is the surface tension per unit of length in newtons/meter
d is the length of the object (m).

Question: Can you explain why F depends on the length of the object rather than the total surface area of the object being pulled from the surface of the object? My project is entitled "Measuring the surface tension of water" in your portfolio of experiments.

Tia

Paul

Try looking in bibliography of the experiment writeup:

http://www.newton.dep.anl.gov/askasci/p ... y00656.htm

Here is a more complete explanation on surface tension:

http://en.wikipedia.org/wiki/Surface_te ... efinitions

Hope this helps clarify the subject. This is an important topic with lots of implications, so it is a great project. Good luck on your project.