B When do marbles behave like a liquid in a beaker?

[beamthegreat]

TL;DR

If we place a cork in a beaker then filled the beaker with normal-sized marbles, the cork will remain stationary at the bottom of the beaker. However, if we continuously decrease the size of the marble, at a certain point, the marbles will behave like a liquid and the cork will rise to the top of the beaker. When does this happen and why?

If we place a cork in a beaker then filled the beaker with normal-sized marbles, the cork will remain stationary at the bottom of the beaker. However, if we continuously decrease the size of the marble, at a certain point, the marbles will behave like a liquid and the cork will rise to the top of the beaker. When does this happen and why?

 

[anorlunda]

That sounds like a simple question, but it is not. The complete story is very complicated.

The thing that determines whether a collection of molecules is a solid, liquid, or gas is interatomic spacing and interatomic forces. Those thing depend on temperature and pressure. Have a look at the following diagram.

If you would like to learn more about I recommend starting with this Wikipedia page. A bowl full of marbles is far too complicated to learn from.

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

 

[Baluncore]

When does this happen and why?

If the marbles are all the same size, they will pack the same way and have the same density, independent of diameter.

The amplitude of local noise or vibration relative to diameter, will be important in causing the marbles to move against each other, and so flow down around the cork.

Lubrication of the marble surfaces will also be important.

 

[Andy Resnick]

Summary:: If we place a cork in a beaker then filled the beaker with normal-sized marbles, the cork will remain stationary at the bottom of the beaker. However, if we continuously decrease the size of the marble, at a certain point, the marbles will behave like a liquid and the cork will rise to the top of the beaker. When does this happen and why?

If we place a cork in a beaker then filled the beaker with normal-sized marbles, the cork will remain stationary at the bottom of the beaker. However, if we continuously decrease the size of the marble, at a certain point, the marbles will behave like a liquid and the cork will rise to the top of the beaker. When does this happen and why?

As @anorlunda mentioned, it's not so simple. The settling of a fine powder is a heavily-researched topic, as is "fluidized beds". I believe that powder sedimentation is a logarithmic process- the powder does not become 'fully settled' in a finite time.

https://www.pnas.org/content/112/1/49

https://www.sciencedirect.com/science/article/pii/S0307904X08000875

Not to be forgotten is the "Brazil nut effect":

https://www.nature.com/articles/429352b
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.92.114301