When do marbles behave like a liquid in a beaker?

In summary, the cork will rise to the top of the beaker when the amplitude of local noise or vibration relative to diameter becomes greater than the force of gravity. This happens when the marbles start to lubricate their surfaces and the powder becomes less dense.
  • #1
beamthegreat
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TL;DR 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?
 
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  • #2
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.
1630504059646.png


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
 
  • #3
beamthegreat said:
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.
 
  • #4
beamthegreat said:
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
 
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1. What is the concept of buoyancy?

Buoyancy is the upward force exerted by a fluid on an object that is partially or fully immersed in it. This force is equal to the weight of the fluid that the object displaces.

2. How does the buoyancy thought experiment work?

In the buoyancy thought experiment, a hypothetical object is placed in a fluid, and the forces acting on the object are analyzed to determine whether it will float or sink. This experiment helps us understand the concept of buoyancy and how it applies to real-life situations.

3. What factors affect an object's buoyancy?

The buoyancy of an object is affected by its density, the density of the fluid it is placed in, and the volume of the object that is submerged in the fluid. Objects with a lower density than the fluid will float, while those with a higher density will sink.

4. Can an object float in a fluid with a higher density?

Yes, an object can float in a fluid with a higher density if the object's shape allows it to displace a greater volume of fluid than its own weight. This is why a ship, which has a lower density than water, can float on the surface of the ocean.

5. How is the concept of buoyancy used in real life?

The concept of buoyancy is used in many real-life applications, such as designing ships and submarines, determining the weight of objects, and understanding the behavior of hot air balloons and blimps. It is also used in industries such as oil drilling and underwater construction to lift heavy objects from the ocean floor.

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