Comments on: Brazil nut effect: why larger mixed nuts "float" to surface http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html Brain candy for Happy Mutants Wed, 19 Jun 2013 14:34:00 +0000 hourly 1 http://wordpress.org/?v=3.4.1 By: ROSSINDETROIT http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951041 ROSSINDETROIT Wed, 30 Nov -0001 00:00:00 +0000 #comment-951041 In an agitated container, material circulates by rising at the sides and falling at the middle. This is due to friction against the sides, where it's easier to push something up than down. In an agitated container, material circulates by rising at the sides and falling at the middle. This is due to friction against the sides, where it’s easier to push something up than down.

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-954129 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-954129 What would explain why after digging in your garden getting rid of any sizable rocks, the next year more have moved their way up to the surface? What would explain why after digging in your garden getting rid of any sizable rocks, the next year more have moved their way up to the surface?

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951136 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-951136 I've noticed this effect here at the beach in Oregon, and tried to explain it to people who dig to find the big agates. Mostly, if there are big ones washed up, they'll be right on top or in the first couple inches of gravel. Below that, it's all pretty uniformly sand. I’ve noticed this effect here at the beach in Oregon, and tried to explain it to people who dig to find the big agates. Mostly, if there are big ones washed up, they’ll be right on top or in the first couple inches of gravel. Below that, it’s all pretty uniformly sand.

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951400 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-951400 I 100% agree. I am currently DOING a PhD into size and density segregation of granular materials. We know very little about the mechanisms which drive these kinds of segregation, but what we do know seems to indicate that there is a different reason for each of the examples shown. I 100% agree. I am currently DOING a PhD into size and density segregation of granular materials.

We know very little about the mechanisms which drive these kinds of segregation, but what we do know seems to indicate that there is a different reason for each of the examples shown.

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951154 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-951154 I just don't want to Troll. But this is a rather complex problem, with multiple factors contributing to the effect. No full model has yet been deviced explaining the phenomena in full. Though approximations have been made. I'm brave enough to say I don't fully understand the effect. (Little side note: I do have PhD in theoratical physics) I just don’t want to Troll. But this is a rather complex problem, with multiple factors contributing to the effect.
No full model has yet been deviced explaining the phenomena in full. Though approximations have been made.
I’m brave enough to say I don’t fully understand the effect.
(Little side note: I do have PhD in theoratical physics)

]]> By: Ugly Canuck http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951446 Ugly Canuck Wed, 30 Nov -0001 00:00:00 +0000 #comment-951446 Want to sort your nuts? Then shake shake shake senora: http://www.youtube.com/watch?v=Bk3sLHZzZRI That'll sort them out! Want to sort your nuts?
Then shake shake shake senora:

http://www.youtube.com/watch?v=Bk3sLHZzZRI

That’ll sort them out!

]]> By: CastanhasDoPara http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951472 CastanhasDoPara Wed, 30 Nov -0001 00:00:00 +0000 #comment-951472 Huh, interesting... now I know why I always seem to end up on top after being agitated. Huh, interesting… now I know why I always seem to end up on top after being agitated.

]]> By: Aenieron http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-952242 Aenieron Wed, 30 Nov -0001 00:00:00 +0000 #comment-952242 Why is there a patern? from the other experiment shown, the larger objects (e.g. Washers) clustered together, but in his last experiment, they spread into a uniform partern, is this because of the horizontal motion, with the earths gravity forcing the breakup of the energy in different places? (non phd, just curious XD) Now to use again evolutionists, just because you have all the parts of a watch in a box and start shaking it, doesn't mean you have a watch. Why is there a patern? from the other experiment shown, the larger objects (e.g. Washers) clustered together, but in his last experiment, they spread into a uniform partern, is this because of the horizontal motion, with the earths gravity forcing the breakup of the energy in different places? (non phd, just curious XD)

Now to use again evolutionists, just because you have all the parts of a watch in a box and start shaking it, doesn’t mean you have a watch.

]]> By: Aenieron http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-952246 Aenieron Wed, 30 Nov -0001 00:00:00 +0000 #comment-952246 An interesting way to test this would to try it in a zero G environment. An interesting way to test this would to try it in a zero G environment.

]]> By: ROSSINDETROIT http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951010 ROSSINDETROIT Wed, 30 Nov -0001 00:00:00 +0000 #comment-951010 An easier way to see this is that smaller particles have more density for the volume that they occupy because there's less air between them. Therefore when agitated the large particles 'float' on them. Worked that one out a long time ago. Speaking of particle physics, I'm 90% of the way through Lisa Randall's book Warped Passages, about strings, branes, extra dimensions & related difficult things. It's been educational, but the next time Gareth Branwyn tells me to read something I'll scan before I buy. An easier way to see this is that smaller particles have more density for the volume that they occupy because there’s less air between them. Therefore when agitated the large particles ‘float’ on them. Worked that one out a long time ago.
Speaking of particle physics, I’m 90% of the way through Lisa Randall’s book Warped Passages, about strings, branes, extra dimensions & related difficult things. It’s been educational, but the next time Gareth Branwyn tells me to read something I’ll scan before I buy.

]]> By: howaboutthisdangit http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951015 howaboutthisdangit Wed, 30 Nov -0001 00:00:00 +0000 #comment-951015 It is easier for small particles to fall through the gaps between large particles than the other way around. It is natures own sieve sort. It is easier for small particles to fall through the gaps between large particles than the other way around. It is natures own sieve sort.

]]> By: Aknaton http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951792 Aknaton Wed, 30 Nov -0001 00:00:00 +0000 #comment-951792 I like to take this as a comprehensible example of decrease of entropy in a non-closed system (energy is being added to agitate). Now use it against creationists who insist that life couldn't have evolved, because entropy would have overtaken any evolutionary advances. (The Earth is not a closed system.) I like to take this as a comprehensible example of decrease of entropy in a non-closed system (energy is being added to agitate).

Now use it against creationists who insist that life couldn’t have evolved, because entropy would have overtaken any evolutionary advances. (The Earth is not a closed system.)

]]> By: scottunder http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951025 scottunder Wed, 30 Nov -0001 00:00:00 +0000 #comment-951025 I remember reading about this many years ago in Scientific American. As #2 suggests, the explanation that stayed with me is that when gaps open up during vibration, small particles can fit in any size gaps, but big particles cannot, so small things end up under big things. Another place this effect shows up is in rocky agricultural land, where farmers still remove boulders in fields that have been plowed for centuries. I remember reading about this many years ago in Scientific American. As #2 suggests, the explanation that stayed with me is that when gaps open up during vibration, small particles can fit in any size gaps, but big particles cannot, so small things end up under big things.

Another place this effect shows up is in rocky agricultural land, where farmers still remove boulders in fields that have been plowed for centuries.

]]> By: ROSSINDETROIT http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951026 ROSSINDETROIT Wed, 30 Nov -0001 00:00:00 +0000 #comment-951026 In an agitated heterogeneous material the particles form 'cells' of rising and falling material. All material rises with equal ease but the largest particles find it more difficult to circulate back down because they have a large bottom surface area, is another way of looking at it. In an agitated heterogeneous material the particles form ‘cells’ of rising and falling material. All material rises with equal ease but the largest particles find it more difficult to circulate back down because they have a large bottom surface area, is another way of looking at it.

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951027 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-951027 Granular convection is a phenomenon where granular material subjected to shaking or vibration will exhibit circulation patterns similar to types of fluid convection. Under experimental conditions, granular convection of variously-sized particles has been observed forming convection cells similar to fluid motion. The convection of granular flows is becoming a well-understood phenomenon. In geology, this phenomenon is one of the causes of inverse grading which can be observed in many situations including soil liquefaction during earthquakes or mudslides. Brian Raymond Callahan Orlando, Florida Granular convection is a phenomenon where granular material subjected to shaking or vibration will exhibit circulation patterns similar to types of fluid convection.

Under experimental conditions, granular convection of variously-sized particles has been observed forming convection cells similar to fluid motion. The convection of granular flows is becoming a well-understood phenomenon.

In geology, this phenomenon is one of the causes of inverse grading which can be observed in many situations including soil liquefaction during earthquakes or mudslides.

Brian Raymond Callahan
Orlando, Florida

]]> By: xzzy http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951028 xzzy Wed, 30 Nov -0001 00:00:00 +0000 #comment-951028 Any kid with a bucket of lego understands this intuitively. My parents stored my pieces in those clear plastic containers that fit under beds.. I spent a lot of time holding them above my head trying to find specific tiny pieces. These days I use the behavior a bit differently.. I put all my pieces in a ziploc bag, seal it, shake it around a bunch, let the stuff settle naturally. Then I scoop off the top layer of big pieces, makes pawing through the remaining tiny pieces a lot easier. Any kid with a bucket of lego understands this intuitively.

My parents stored my pieces in those clear plastic containers that fit under beds.. I spent a lot of time holding them above my head trying to find specific tiny pieces.

These days I use the behavior a bit differently.. I put all my pieces in a ziploc bag, seal it, shake it around a bunch, let the stuff settle naturally. Then I scoop off the top layer of big pieces, makes pawing through the remaining tiny pieces a lot easier.

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951029 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-951029 God is a fan of big nuts... so they are summoned to the top to keep relevant. God is a fan of big nuts… so they are summoned to the top to keep relevant.

]]> By: Lobster http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951032 Lobster Wed, 30 Nov -0001 00:00:00 +0000 #comment-951032 You can see this at work in modern culture, too. Shake things up and the biggest nuts come out on top. ;) You can see this at work in modern culture, too. Shake things up and the biggest nuts come out on top. ;)

]]> By: Anonymous http://boingboing.net/2010/11/29/brazil-nut-effect-wh.html#comment-951035 Anonymous Wed, 30 Nov -0001 00:00:00 +0000 #comment-951035 Cat owners also know this. Shake the litter pan and the clumped bits come to the surface. Much easier for cleaning that way. Cat owners also know this. Shake the litter pan and the clumped bits come to the surface. Much easier for cleaning that way.

]]>