2
$\begingroup$

When you pour sand into water, first the dust particles that are floating on the surface, are separately all over.

enter image description here

Then as the water flows, the dust particles should just randomly move around staying mostly separately, but for some reason, all the dust particles are moving together and sticking together into islands, just like planets are formed from dust in the solar systems.

enter image description here

It is like there was some force that is pulling these dust particles together, and keeping them in these islands. Is this the same Van der Waals force that keeps the water molecules together?

https://en.wikipedia.org/wiki/Van_der_Waals_force

Question:

  1. Why are dust particles moving together into these islands on top of the water?
$\endgroup$

marked as duplicate by John Rennie electromagnetism Oct 20 at 15:57

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ if it was the van der waal’s forces doing, shouldn’t the dust clump into islands even if the water didn’t flow? +1 $\endgroup$ – Ubaid Hassan Oct 20 at 15:53