Fancy a Quickie?
A bit of a change for SEx Education this week, as we look at three questions posted on the SEx Forum that, miraculously, turned out to have nice, simple answers1.
I Can 'c' the Light
Why is the letter c used for the speed of light?
The answer was supplied by your correspondent:
Apparently, it all stems from when force laws were first developed by Weber, who used c in his equations to mean 'constant'. The value of c was later discovered to be related to the speed of light, and subsequently redefined *as* the speed of light, after which it gradually came to replace the previously used V (presumably 'velocity'), most famously when Einstein used it in his equation E=mc2
Gunge Gets in Your Eyes
In our second question, Apollyon deals with something we've all encountered, but which isn't often discussed in polite society.
You know when you wake up and there's that yellow stuff in your tear ducts? What is it, what is it made of, and where does it come from?
First with an answer was Gnomon:
It comes from your tear ducts. It is the lubricant that keeps your eye from sticking, but as the water in it evaporates, the stuff that is left turns into sticky goo. During the day, you wipe your eyes without thinking about it, but when you're asleep you don't do this, so it accumulates into hard lumps3.
Why is it that aluminum foil is cool enough to touch when it comes out of the oven?
The ever-reliable Gnomon was on hand once more to supply an answer:
Foil is so thin that it can't transmit heat along the foil quickly. Although the foil is at a very high temperature, there's only a small amount of heat in it, because there's such a small amount of foil beside your finger. So the foil reduces in temperature a lot and your finger heats up a little bit.
So there you have it. Whether it's big or small, hard or easy, long or short, the SExperts can help you out.