Non-Newtonian fluids and Oobleck
Found this very interesting video of a non-newtonian fluid, and it’s reactions to the vibrations produced by sound. Reminded me a lot of the Cymatics video I posted about last month. Non-Newtonian fluids are liquids that under some conditions act as solids.
The term Oobleck, a fictional substance from a Dr Seuss book, is often used to refer to a corn starch based non-newtonian fluid. You can make your own by mixing corn starch with water until it starts to get a creamy almost pudding look. The mixture will remain a liquid as long as any movement or force applied to it is slow. But as soon as you apply a rapid force, it will behave like a solid. The video below demonstrates the principle. An entire pool was filled with a mixture of cornstarch and water. As you can see, people can run and even jump up and down on it. But as soon as they stop moving, they sink.
The following video is pretty dry, but it is a bit more scientific and controlled than the two above.
Way cool!
My brother and I did a science fair project on non-Newtonian fluids when we were growing up. Wish we had known about the sound part — at least we didn’t demonstrate it. We did have bowls of cornstarch mixture (dyed green of course to make it look better.) One thing we did learn is that there are some non-Newtonian fluids that act the opposite of this cornstarch mixture — butter, for example.
Yes, Oobleck was among my favorite Dr. Suess stories.