One type of body armor uses a solution of polymer particles soaked into porous fiber ordinarily flexible, the impact of a bullet turns it solid. Important examples of this type of material include drilling mud used in oil wells and fluid used to couple automobile transmissions to the wheels. This phenomenon, called “shear thickening,” occurs in materials made up of microscopic solid particles suspended in a fluid. On YouTube you can find videos of people running across pools filled with Oobleck: The pressure of a foot striking the surface causes the liquid to thicken under it enough to support the runner. Hit it hard enough, say with a hammer, and it instantly hardens enough to shatter. The harder you stir it, the thicker it gets and the more it resists your stirring. It’s a “non-Newtonian” fluid that doesn’t respond to outside forces the way you’d expect. Seuss story – is just a thick solution of cornstarch in water, but it’s not as simple as that sounds. Oobleck – named by the creators of the popular grade-school project for a gooey substance that fell from the sky in a Dr. Cornell physicists have finally explained what makes Oobleck so weird. Next time, you can just have fun with it, knowing that the argument is over. If your kids ever brought home some Oobleck from school, you had a glimpse of a long-standing scientific controversy.
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