281 upvotes, 5 direct replies (showing 5)
View submission: Is sand a liquid???
No. The most important way that sand isn't a liquid is that you can make a pile of it. It *doesn't* always take the shape of its container, a small amount will form a self-supporting hill. As you add more that hill gets bigger but keeps the same steepness ( "angle of repose"[1] ). You can't make a pile of a liquid: given enough time, even the thickest and most viscous[2] liquid will have a flat surface on top.
1: https://en.wikipedia.org/wiki/Angle_of_repose
2: https://www.merriam-webster.com/dictionary/viscous
Technically, we say that granular materials like sand have "static shear strength[3]" while liquids do not: when subjected to forces that try to slide part of the material past another part, granular materials can stay still, but liquids always move.
3: https://en.wikipedia.org/wiki/Shear_stress
Comment by petripooper at 16/01/2024 at 17:55 UTC
13 upvotes, 1 direct replies
Is there a clear line between granular material and liquid? or is it a continuous transition?
Comment by Frites_Sauce_Fromage at 17/01/2024 at 08:15 UTC
2 upvotes, 1 direct replies
So sand isn't liquid but what about the study that were claiming that cats are liquid?
Comment by Mockingjay40 at 18/01/2024 at 22:12 UTC
2 upvotes, 0 direct replies
Rheologist here, this is correct. Fluids have to have a relaxation time, and sand does not.
Comment by liquid-handsoap at 16/01/2024 at 19:27 UTC
-32 upvotes, 2 direct replies
That just sounds like surface tension. Like a droplet wont flat itself out either
Comment by Racoon_withamarble at 17/01/2024 at 13:30 UTC
1 upvotes, 0 direct replies
What if all the particles were vibrating like molecules?