I mean I read that surface tension is the property of a liquid by virtue of which liquid tends to have minimum surface area and behaves as if it was covered with a stretchable membrane.

  • Why does a fluid has to bear surface tension?

  • And even if it has to then what are the benefits? I wish to know if there are any advantages of surface tension.

  • And is surface tension dependent on properties like density and viscosity?

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    $\begingroup$ How do you define a benefit? This seems a bit subjective. In some instances it is useful (spilling is less probable), in others it is not (exact measurements). Surface tension is just a result of Newton's laws when considering each individual fluid particle - and asking what the benefits of Newton's laws are is equally subjective. $\endgroup$ – Steeven Jan 7 '19 at 6:34

The thing we call surface tension exists because the molecules of a liquid usually have a certain amount of (weak) attraction for one another. That attractive force is distributed amongst each molecule's nearest neighbors in the bulk.

The situation at a free surface is different; right at the surface, each molecule has only half as many nearest neighbors and the attractive force gets distributed across only half as many molecules. This makes that force proportionately stronger at the free surface, which is why it behaves like a stretched elastic membrane.

What "good" is surface tension, then? Well, it is responsible for capillarity, which is the tendency for liquids (like water) to "wick up" and get absorbed into fabric and things like paper towels and toilet paper, and to climb up against gravity in fine-bore tubes.

  • $\begingroup$ To add to niels' answer, capillarity is CRUCIAL if land plants are going to get water from ground level up to their leaves, where the water, CO2, and sunlight combine to make glucose. Since plants are at the bottom of the food web, most higher level land based organisms would not exist without capillarity. $\endgroup$ – David White Jan 7 '19 at 16:46
  • $\begingroup$ actually, plants actively transport water up and out of their roots; you can see this by calculating the pore diameter required to lift water to the top of a 350' tall redwood ;-). $\endgroup$ – niels nielsen Jan 7 '19 at 18:59
  • $\begingroup$ I realize that the trees taller than 34 feet have to actively transport water up their stems. Do very short trees and shrubs have to do this? $\endgroup$ – David White Jan 7 '19 at 21:43
  • $\begingroup$ I believe they do but cannot prove it. what I do know is that the tissue that performs this task is called xylem. $\endgroup$ – niels nielsen Jan 7 '19 at 22:57

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