Build your own avalanche disk to observe granular physics in action.  A single granule is a solid but when it interacts with many, it may behave as a solid, liquid, or gas.

I first saw one of these a while back in some science museum that I took Caitlin to.  It was more of an art installation where I thought the inside was like one of those lava lamp fluid things.   I recently saw a related video to an avalanche disk and it looks like  The Museum of Science and Industry - Chicago has one on display.  Theirs is 20 ft in diameter and weighs several tons.  This one scaled way down. It's one of those things - "How did they do that?" but more importantly, "Can you make it at home?"  Other than that, there is a field of science that applies to this.

Learning Objective: Build and use an avalanche disk to observe the behavior of granular solids as granules flow, shear, mix, separate and freeze.

Knowing how granular solids act is pertinent to helping you predict/prevent snow avalanches to designing machines to package your cereal.  Computer modelling can be quite complex.

Video of the Avalanche Disk in action (overdub with your best Carl Sagan impression on the creation of the universe):

Step 1: Apparatuses or apperatii?

You will need:

Some sort of rotating base:
I found this rotating artist's turnstyle stand at a discount store.  The rotation is manually powered by hand but something like a motorized potter's wheel or old-fashioned LP record player turntable(don't know if it has enough torque for heavy loads) would be better.  I was thinking of attaching my container to a sanding disk that is chucked up in a power drill.  You can also build a rotatable base with a lazy-susan turntable or mechanism (IKEA has lazy-susan turntables - I was planning to make a wheel of fortune or casino spinner with one)

Some sort of container for your media:
I found this clear plastic half dome container for storing lettuce halves.  It has a dome cover I could put on but any round flat bottom container with a low wall would suffice.  A cover is nice so you don't have a toxic spill with the media.  You can use the upper half of a CD/DVD spindle cover.

Granular solids:
The museum exhibit description says it uses a mix of glass beads and red garnet sand.  I do not know what size grain they use but I remember ibles using glass microbeads for its reflective properties.  Harbor Freight is a source for a bulk amount of glass microbeads.  I got the smallest(25lb container, around $25 US) of 80 grit glass microbeads used for sandblasting.  The stuff feels like a smooth powder and is quite fine.  The craft store that sells you a thimble full for glitter work is too expensive. I don't think you would want to inhale any of it and getting some on the floor makes it a slipping hazard.  Keep it contained and work deliberately with it.  I think I only used a few ounces of the product and have a lot to use on other projects such as painting a reflective stripe in my driveway(this may be the stuff they dust the street white lines after painting).

I also got a bag of red colored play sand, the stuff used for sand sculptures you fill in bottles.  It is also quite fine in texture.

<p>That's pretty cool! Thanks for showing me this. So the different sands have a different specific gravity and never really mix. I like the idea of the stargate table too :)</p>
<p>Thanks. It's great fun to figure out how things work and see science in action.</p>
I suggest adding a motor to the avalanche disk! ;P
For your &quot;Apparatuses or apperatii?&quot; question, the plural of the noun apparatus is apparatuses, although in this context just apparatus should suit you fine!
I do that for the fun anonymousii comments.
And so you should, commenti such as that are inspirational, and we need more inspirati in our lives.
Sweet! I remember seeing one of these at the Tec Museum but I never knew what the scientific name was for them. Thanks for the info!
I thought it might have also been some kind of ferro-fluid. One more mystery of the universe revealed.

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