When you pour sand into water, first the dust particles that are floating on the surface, are separately all over.
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.
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:
- Why are dust particles moving together into these islands on top of the water?
