Oobleck is a funny word

As most of you totally serious scientists who regularly come here certainly know, oobleck, which is a saturated solution of cornstarch and water, is a non-newtonian fluid which displays some quite amazing characteristics.

For the totally serious scientist types who regularly come here and do not know what a non-newtonian fluid is (the void is shrinking!), a non-newtonian fluid is one which displays varying degrees of viscosity at any given temperature depending on the force that is being exerted upon it. In this case, you might be able to run on the surface of oobleck, but not walk. This is because, as you run, the force at which your feet strike the surface is usually enough to make it so viscous it will seem nearly solid. In fact, it might not even break up the surface tension, leaving you dry after running across a body of liquid, but, as you walk, the force of your calm, slow steps is much slower, and you might sink. Tragically (oh noes!), as you struggle to break free of the vicious - sorry, viscous - Oobleck (what, is a great name for a monster!), the force of your squirming might make it viscous enough to trap you, just like quicksand is rumored to behave.

On the smaller, lighter scale, you can so dome neat things, such as pouring a little on the cupped palm of your hand. It will feel and slosh about like a liquid (which it is), but the moment you try to roll it up into a little ball like you might do with silly putty or modelling clay, it will take a shape - until you stop rolling it, that is, at which point it will instantly revert to oozing out of your hands like light honey. You can also make it bounce off walls and floors - so long as you don't even consider enlisting my services or even my help to clean up after your science (fluid dynamics is, after all, a branch of physics, and, thus, totally serious science).

Here's a recepy for disaster: mix up a batch of oobleck. If you don't know how, then I'm fining you in one free internet, to be collected at my lesiure, but, out of the kindness of my heart, allow me to explain: pour about half a cup of cornstarch into a bowl and add just a little water. Stir slowly. At first, you'll get nothing but hard clumps, and nothing even remotely similar to a fluid, newtonian or otherwise. Preservere, and resist the tentation to add more water right away, but go on and add small amounts from time to time, stirring all the way as you go. Eventually, you might get a runny liquid you have absolutely no trouble at all stirring. That's when you know you've added too much water. No problem, just keep adding more cornstarch until you have a coveted non-newtonian fluid. You'll know you're there when it feels like you're breaking up clumps of the flour in the bottom of the bowl (as the resulting liquid will me a milky beige, you won't be able to confirm or deny the presence of said clumps by sight) if you stir as you'd usually do, but you'll feel no such resistance if ou stir very slowly. Alternatively, you might want to stir with your fingers. This will give you a much more accurate feeling for clumps or lack thereof, and some might find it more fun, but it's a bit messier. At this point, quickly strike the surface of the liquid. If you're at the right point, it should bend, but not allow the striking object (spoon, whisk, finger) to penetrate as easily as a regular liquid (or, as totally serious scinetist would call it, a newtonian fluid) would. If not, keep adding more cornstarch and stirring.

Now, let's make something a bit more fun: get some balloons and put them inside one another like a Matrioska (which, in case you don't know, is a hollow doll which you can open at the waist to reveal a smaller version of itself which contains yet a smaller version of it self and so on a few times. Even though these are most commonly associated with Russia, I distinctly recall reading somewhere that they are originally Indian, but so popular in Russia that they would be commonly know as typically Russian. I won't swear by this). Now fill the innermost ballon with the oobleck you just made. If you want a small finished product (about the size of an uninflated balloon), just pouring the goo inside with a funnel will do, but that's hardly any fun. Instead, pour as much as you want inside the balloons into an empty bottle. then blow some ait into the innermost balloon and clamp the neck as low as you can with a clothespin or something to that effect. Carefully stretch the unclamped portion of the neck over the neck of the loaded bottle and secure it with your fingers and thumb, just to be on the safe side. Unclamp the balloon, turn the bottle upside down and wait until all of the oobleck has poured into the balloon. As the air will have to bubble through the (slowly) oozing goop, this will take a little while. Then tie off the innermost balloon and cut off the excess rubber above the knot. SO this for all of the other balloons and presto, a dirt cheap stress ball. This fun little thing will feel very soft if you squeeze it slowly and gentrly, but if you squeeze it quickly and hard, you'll feel it harden against your fingers and very slowly brwak under the pressure.

Note: The most lonely of the totally serious science types who regularly come here should note that this is a poor substitute for a woman's berast. Try this instead.

And now, the disaster: Before I perfected the process of making these little stress balls, I had a balloon with over half a pint of oobleck burst over a shag rug. As I finished panicking, I realised I couldn't just hold it over my tub and rinse it off, as this mixture will percipitate if left undisturbed for long, and clog up your pipes. Always dispose of it in plastic, sealed bags. Then I remembered I should just pick up the rug and pour the oobleck into a large bowl to re-use it. That's when I found out about a property of oobleck I didn't know about: if left undisturbed for even a minute, it will gain a nearly solid skin. I found out about this as it wouldn't ooze into the bowl, and when I touched it, it had about the same consistency as cake icing, but it "melted" into its more familiar texture as soon as I broke off the little pieces.

Pax vobiscum atque vale.

ArabianShark is considering the possibility of brewing up some hand analogues from unflavoures, unsweetened gelatin and latex gloves for casts.

3 comments:

RaymonLosey said...

與其爭取不可能得到的東西,不如善自珍惜運用自己所擁有的..................................................

好想談戀愛 said...

笑口常開~~天天開心.........................

腰痠 said...

人生是故事的創造與遺忘。 ..................................................