You can calculate surface tension by dividing the force (F) over the unit length (l) where it acts and the cosine of the angle (cosθ) of that length where the force is acting.
So the equation looks something like this:
Surface Tension = F / (l * cosθ)
However, each liquid has a defined surface tension at each individual temperatures.
As we went over, the surface tension of water at 20 degrees Celcius (room temperature) is 0.073 N/m. At 100 degrees, it's 0.059.
In most problems you'll encounter dealing with surface tension, you'll be given a few of the variables and be asked to find the missing pieces.
An example problem would be something like this: find the surface tension of a liquid that as a force of 50 Newtons acting over 10 mm at a 30-degree angle.
You can then use the units of surface tension and your knowledge of force and unit conversion to calculate the surface tension.
The solution would look something like this:
Surface Tension = Force / (length * cosθ)
= 50 N / (0.01 m * cos(30))
= 50 N / (0.01 m * 0.0867)
= 5767.01 N/m
This one example shows how you can use given variables to find the surface tension of liquids.
You might also be asked to use the known surface tension of liquids to find the weight of objects resting on it, the length at which a force is acting, and more.
Once you know the formula and the units, this should be simple math. And you can use our conversion calculators if you need a little help.
Surface tension can be a complex topic to understand as it involves concepts from chemistry, physics, and math.
Hopefully, this guide helped make sense of this topic so you can successfully solve problems and get through your work.