SEx Education: Fancy a Quickie?

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Science Explained

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

Our first question comes from SEx founder icecoldalex, who was asked this question by one of her students2:

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.

Foiled Again

Finally, we're back in the kitchen4, as noivilbo wonders...

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.


This article was based on a conversation at the SEx forum - where science is explained.

Why not pop over with your own questions? The pick of the bunch will feature in The Post's next

SEx Education Archive

Danny B.


Back Issue Page

1Don't worry — we won't let it happen again.2Causing Mu Beta to complain that 'My students never ask intelligent questions'.3Of course, if you find you're waking up with large amounts of yellow/green deposits in your eyes, it might be worth a trip to your GP in case you have conjuntivitis or another infection.4Where we have previously made coffee of varying temperature and boiled saucepans with and without lids.

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