These very short videos are showing, that the sand and powder can behave sometimes like fluid and sometimes like solid.
1.01 – Pile and weight
The video shows that the sand can be poured like liquid, but when poured creates a slopy pile, which can support a strong load.
1.02 – Saltshakers
Paradox: the water has problems to flow out of soltshaker, while the sand flows better than liquid
1.03 – The powder droplets
Powder flows down the tilted surface similar to water droplets
1.04 – The powder tube
This video shows, that the powder contains air.
1.05 – The bouncing powder tube
The air cannot escape from powder and makes powder elastic and bouncing
1.06 – The vacuum cleaner and the glove
When the glove is filled with powder and the air is sucked from glove with vacuum cleaner (with filter in the tube), the shape behaves as solid. It the air goes bac in glove, the powder softens. The less air the more solid, the more air the more “liquid”.
1.07 – Compacted and aerated powders
The stone bounces from the surface of compacted powder – powder behaves like solid. If you let the stone in areated powder it drops into powder. The proportion of air in powder changes its behaveour.