Scientists Say: Surface tension

This effect is what allows some bugs to walk on water

water striders

Surface tension creates just enough cohesion to hold up tiny bugs — like these water striders.


Surface tension (noun, “SUR-face TEN-shun”)

This is an effect seen when liquid meets air. The molecules in the liquid are more attracted to each other than they are to the nearby air. This makes them clump together at the liquid’s surface. Surface tension is what makes the surface of a very full glass of water look like it is covered with an invisible membrane. It’s also why some small insects can walk on top of the water — surface tension is just strong enough to hold them up.


In a sentence

Soap can disrupt surface tension by making it harder for the water molecules to bunch together.

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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