# Engineering Dopers- Question about cornmeal/physics

**URL:** <https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138>\
**Category:** Factual Questions\
**Created:** [March 9, 2003, 8:57pm UTC](https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138 "2003-03-09T20:57:39Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\
**Post date:** [March 9, 2003, 8:57pm UTC](https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138/1 "2003-03-09T20:57:39Z")

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I am interested in the property of a cornmeal/water mixture by which increased pressure causes the mixture to solidify. I think this was a demonstration of some property from high school physics. What is this propery called?

I’m also interested in other substances that have this property. Is there some substance that could be put into a flexible container like a ziplock bag, that would offer more resistance to bending at high pressures, but not as much at low pressures?

Sorry I’m so vague. I searched Google and SDMB for a while, but all I got were recipes for mush and gruel.

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**Author:** ![TheNerd](https://avatars.discourse-cdn.com/v4/letter/t/858c86/32.png) [@TheNerd](https://boards.straightdope.com/u/TheNerd)\
**Post date:** [March 9, 2003, 9:01pm UTC](https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138/2 "2003-03-09T21:01:09Z")

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I’ve heard such substances described as “non-newtonian” fluids. I remember seeing a demonstration on Letterman (or maby Leno).

There was also some discussion on a site called [half-bakery.com](http://half-bakery.com) about using such fluids to fill speed bumps. At low speeds, they wouldn’t really impede progress, at high speeds, they’d be nearly solid.

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**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\
**Post date:** [March 9, 2003, 9:09pm UTC](https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138/3 "2003-03-09T21:09:08Z")

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these are called shear-thickening (or dilatent) fluids. Cornstarch water or wet sand are the best known. there are several explanations for this behaviour, one is that the water is squeezed out under pressure, causing the particles to stik together

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**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\
**Post date:** [March 10, 2003, 8:37pm UTC](https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138/4 "2003-03-10T20:37:15Z")

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Ah yes dilatent fluids! Thank you **scm1001**. Anyone know of other such fluids or websites where I could find some good research being done on them?

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**Author:** ![Trigonal\_Planar](https://avatars.discourse-cdn.com/v4/letter/t/0ea827/32.png) [@Trigonal\_Planar](https://boards.straightdope.com/u/Trigonal_Planar)\
**Post date:** [March 10, 2003, 10:04pm UTC](https://boards.straightdope.com/t/engineering-dopers-question-about-cornmeal-physics/160138/5 "2003-03-10T22:04:47Z")

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Go to google and look up “magic mud”.

Its easy to mix some up. Its a standard elementary school science experiment – and really fun to play with.