Comment by agate_ on 16/01/2024 at 22:41 UTC

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View submission: Is sand a liquid???

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Maybe I'm moving the goalposts, but surface tension is an example of liquids being not exactly perfectly liquid. Still, the static strength of granular materials comes from the *friction* between the grain particles, not their surface tension, so they behave very differently. One way that plays out is that you can build a pile of sand as tall as you like, so long as it's not too steep, but surface tension will never let you make a blob of water more than a few millimeters tall (in Earth's gravity). And on the other hand, you can never make a "drop" of sand that holds together as it falls.

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Comment by Mockingjay40 at 18/01/2024 at 22:16 UTC

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A good thing to note here is that sand doesn't have a surface tension. It's particulate matter. It can "flow" as a pseudo-fluid but in terms of its phase it is a solid. Similar logic can be used to explain that some fluids have yield stresses.