What is the law behind objects separating by size when shaken?

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SUMMARY

The phenomenon discussed is known as the "Brazil Nut Effect," which describes how larger particles rise to the surface when a mixture of different-sized objects, such as rocks or chestnuts, is shaken. This effect occurs due to the percolation of smaller particles through the gaps created by larger particles during shaking. Gravity plays a crucial role, as smaller objects can navigate through the larger gaps formed by the larger objects, while they struggle to pass through the gaps between similarly sized smaller objects.

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  • Understanding of basic physics principles, particularly gravity.
  • Familiarity with the concept of percolation in particle dynamics.
  • Knowledge of the Brazil Nut Effect and its implications in material science.
  • Basic comprehension of particle size distribution in mixtures.
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  • Research the Brazil Nut Effect in detail, including its applications in food science and material handling.
  • Explore the principles of percolation theory and its relevance in various scientific fields.
  • Investigate experiments demonstrating the Brazil Nut Effect using different materials and shaking techniques.
  • Learn about the role of particle shape and size distribution in the behavior of granular materials.
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Students of physics, material scientists, and anyone interested in the behavior of granular materials during mixing and shaking processes.

Moneer81
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hey,

I saw a question on "Who Wants to Be a Millionaire" about a physics law where for example shaking a jar containing a big number of objects (like rocks, or chestnuts) will result in the bigger ones rising to the surface. I never got the chance to find the answer but does anyone know the name of this law so I can google it? or does anyone know how this works?
 
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It's not a "law"; it's an effect: the "Brazil Nut Effect".
 
Percolation, surely?

It's essentially the effect of small particles falling through the gaps between large particles.
 
The gaps are created by the larger material interfacing and colliding with other larger material. Why does the smaller material fall through the gaps?
 
"Why does the smaller material fall through the gaps?"
Gravity
 
Unless the objects are very regular in shape, the large objects have larger gaps between them than the small objects, on average. The small objects can't make it between the gaps between small objects, but can make it between the gaps between large objects.
 

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