[Novalug] OT: video of non-newtonian liquid. (Cornstartch and cold water!?)

James (Jim) Darlack jmdarlack@yahoo.com
Thu Jan 11 14:51:35 EST 2007


I think its simply powdered corn starch and water.
   
  Try mixing a hand full...or several tables spoons, with cold tap water.
   
  Put the mix in the palm of your hand, and queeze it, and it gets rigid.  Relax the pressure, and it will slowly leak thru your fingers.
   
  However, I must admit I have never "played" with the compound in quantities larger than the usual grocery store sized box.
   
  Jim

Nino Pereira <pereira@speakeasy.net> wrote:
  Well, not quite. I don't think its properties vary with strain rate
(i.e., how fast it's stressed) any more than any other slurry.
Instead, its behavior is dominated by magnetic forces, and what you
see in the video comes from a magnetic field that becomes stronger
or weaker, varies with position, etc: there must be a coil
somewhere, and it would help if they gave a current trace through
some magnet coil that (I think) makes all this happen. 

The physics of it is actually very interesting, and
whole books have been written about the material. The one I'm familiar
with is an oil-based slurry of very small (nano, probably) 
iron particles. Besides for fun stuff it's used in rotary vacuum seals.

Nino


On Thu, 2007-01-11 at 12:12 -0500, Ed T. Toton III wrote:
> Thus spake gregory pryzby:
> 
> > http://video.google.co.uk/videoplay?docid=-8183380788103127428
> >
> > You need to watch it for a bit to really understand what this is about. 
> > If you move, you don't sink. If you stop, well, watch and see!
> 
> It looks like it might be based on similar material properties as Silly 
> Putty... if you pull it slowly, it stretches and oozes, but it shatters if 
> struck with a hammer. The solidity varies with how suddenly it's stressed.
> 
> 
> ------------------------------------------------------------------
> - Ed T. Toton III, RHCE --|-- www.necrobones.com -- ed.toton.org -
> ------------------------------------------------------------------
> "The only thing we learn from history is that we learn nothing
> from history."
> -- Hegel
> 
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