Falling Sand

[Jmmatarao213]

Awesome



[duhCider]

How did you guys get my bathing suit?

[pumoo]

ハードコアゆめにっき

[RockN311]

STUUUPPPPPID

[wutdaflek]

Air resistance? I wonder if it would act the same in a vacuum.

Now maybe I'll go RTFA...

[mirshafie]

Seems that they repeated the experiment at low air pressure and humidities and found that while humidity plays an important role in sand droplet formation, air pressure does not.

[tjhynson]

Did he die?

[kevinwhited16]

this is demonstrating the gravitational pull of planets in space. what i dont get is some of the very small particles flew past the large clusters.. I dont think this correctly demonstrates what it is trying to.

[pinoyako717]

i dOnt gEt it .

[BinkieMcFartnuggets]

I never knew sand had so much in common with my feces after a long night of enchiladas!

[TehSnargle]

I hate you.

[Koolzii]

I Concur

[melikeyyeah]

FSG!

[mtgordon]

I'd bet it doesn't behave like this in a vacuum. My guess is that turbulence creates initial irregularities in the stream which are then enhanced by air resistance. Grains at the bottom of a "drop" experience greater drag and are slowed, while grains immediately behind those are effectively drafting.  The drop size is largely a function of the extent of the drafting effect.

[Twigg808]

I don't know for sure if this video is of the experiment done in a vacuum, but they did perform this in a vacuum as well and the grouping still occurs.

[mtgordon]

Yeah, I realized that after I posted. I ended up sending a link to a physical chemist who might be in a better position to theorize on the subject than I am.

[7222Brit]

um...interesting...

[samrusoff]

Maybe this has to do with the fact that when sand is in very fine particles, they mimic the behavior of atoms (even though grains of sand are incomparably larger than atoms) in a liquid and when poured, a stream of sand forms drops the same way other liquids do to increase aerodynamics.

[BeondaPale]

Gravity? Molecular cohesion?

[leglessnotlegolas]

I'm thinking gravity and, unless it's super-special sand, there might be bigger granules than others, drawing the smaller ones to it?

[archaedemos]

very cool. I can see how the planets formed, kinda better.  (:

[faolitaruna]

This could explain formation of asteroids. Planets were made differently.

[kukelz]

AHA.. so everything we see is fake..right.

[wowlaxis]

intresting...

[pubtor]

wow

[addiecody]

Maybye there isnt gravity and they proved the theory of gravity wrong?

[LoveandEqualityToAll]

?????????????????

[HogieMorgan]

ohh now I understand....

[foodaggression]

is it falling in vacuum?

gravitational or fluid dynamic effect?

[diskchrisco]

wtf? lol

[babydock214]

In the beginning the granules are falling faster than the camera but later on it appears the camera matches the granule speed. Curious.

[czechwindboy]

I guess it shows to proof the tendency of matter to clump together?

[alexander255110]

its gravity to each other

[czechwindboy]

you sure? I wouldn't think so little sand has enough mass for gravity to come into play

[yousefamar]

your right czechwindboy, I find it hard to believe that this has anything to do with gravity; the rate of collision of the grains with each other will cause them to go further apart and gravity would have no effect. The sand must be surrounded by some cohesive liquid or something :?

[czechwindboy]

I don' think there is any liquid. There must be something else in play. I'm thinking that the sand lumps together because of friction w/ the air. Perhaps the lumps, up to a certain size, have lower resistance/friction with the air through which they falling.

[faolitaruna]

I don't think so. Van der Wals force and sticky coatings may play mayor role. Gravity works at bodies bigger than kilometer in diameter.

[yousefamar]

true but as far as I know sand, silicon oxide, is a crystal and forms a lattice (right? :P) so so could vdW forces be strong enough to keep them together? let alone pull them together from a distance?

[faolitaruna]

Of course it can't be responsible for pulling from a distance, it works for distances up to 5 angstroms. i don't know how exactly surface of sand grain looks like, but I can imagine it has many "spikes" or "rough edges". I think interactions between two surfaces could be pretty strong and in effect bind grains in the cluster together.

[yousefamar]

Well, if you say so. You seem to know what you're talking about.

[worldwarthreeblues]

fool

[leonidmilman]

3rd comment?

[MagicHandedAlex]

that looks awesome, but kinda weird aswell