"The good is the greatest rival of the best." - Nellie L. McClung
Question #92425 posted on 07/07/2019 5:24 p.m.
Q:

Dear 100 Hour Board,

I think of this question every single morning, and I'm glad I finally remembered to ask.

Let's say I'm finishing up my morning shower and I wring out my washcloth to hang it on the inside of the door. If I had unlimited strength, could I wring the washcloth out so hard that, when I was finished, it was totally dry? In other words, could I force every molecule out of the material so that it was bone dry?

Don't know why. I just think of these weird things.

Thanks.

-Washrag Randy

A:

Dear person,

Let's say your washcloth is made of cotton. Cotton is good at absorbing for a couple of reasons. First, water is a dipole (has an electrically positively charged "side" and a negatively charged "side" to the molecule) and cotton's electric charges are distributed unevenly along its cellulose fibers. These uneven charges cause the water and cellulose fibers to be attracted to each other. Second, the cellulose fibers are structured in such a way that it is easy for water to move along and inside the fibers. This makes it very easy for water to "hang out" on and around cotton.

Wringing your washcloth is twisting. Thus, the force we are applying to the washcloth is torsion. Torsion is comprised of both compression and tension. When you twist the washcloth to get water out, what you are doing is using compression to force the cellulose fibers closer together. This reduces the amount of surface area that the water can "hang out" on. However, because torsion is both compression and tension, we cannot increase the compression without increasing the tension. And, eventually, the tension will cause the washcloth to rip.

I don't know how to do the math to prove it, but I'm certain that the washcloth would rip before every molecule of water will be forced out of the material. If you were going to destroy a cotton washcloth, would you compress it as hard as you could? Or would you pull it tight as hard as you could? The latter, of course. To force every molecule out would mean reducing the spaces between and within the cellulose fibers until they were so small that water molecules are too small to fit inside. That's extremely tiny.

So no, you could not not wring out your washcloth so hard that all the water would be forced out.

But wait.

Let's say, for the sake of fun, that your washcloth has infinite tensile strength and that your hands are infinitely strong. That is, the cloth could never rip and you won't break your bones, rip or burn your skin, or anything like that. The cloth can only be damaged by the compression part of twisting. Let's say that you, with your infinite strength, start wringing the washcloth. The cotton would give off lots of heat. This would make the water turn into steam at about 212 F. So parts of the washcloth that are touching the air would be dry. However, there is still water at the center of the washcloth, which surrounded by several layers. If you don't unravel the washcloth periodically to allow the water inside to evaporate and instead keep squeezing, the cloth is likely to ignite once it reaches 400-750 F, after which you wouldn't have a washcloth anymore.

-Sheebs