MUG DYNAMICS

We've got new mugs in the kitchen. Marketing re-branding or something I suppose, means we can't be drinking tea out of cups with last year's logo on them, so it was out with the old (I saved one from extermination) and in with the new.

The only trouble is, we quickly realised, Louise and I, that the new mugs are not quite as good at keeping tea hot. In fact, tea seems to go cold impossibly quickly in these new-shape fancy receptacles.

I did a little physics and a little maths, and it turns out that there are probably three reasons:

1. The new mugs are wider. In fact, they're one centimetre wider, which might not sound much but it results in an increase of 29% in the surface area. That means that there's 29% more tea facing the atmosphere, evaporating from the surface, producing a much quicker cooling effect.

2. Although the new mugs are wider, they're also the same height as the old ones. This means that you get more tea - in fact you get an increase of 113 cubic centimetres, which is about 28% more tea than before. It takes longer to drink it, resulting in a higher possibility of cold tea.

3. They're not very well insulated. As you know, I use the kettle, and boiling water in one of these doozers makes the outside of the mug way too hot to touch. In fact, I'm not even sure they're made of porcelain any more. That means heat escapes much more quickly from the sides of the mug.

So more tea, but its heat gets dissipated faster through the sides and the top.

There must be an optimum shape for a mug. I mean, drinking tea from a pipe or a kind of porcelain straw would be unbearably hot (literally piping), but the opposite, a kind of wide, flat dish would also be ridiculous. And your puddle of tea would go cold before you could lap it up.

Good job then, that I saved one with last year's logo. I'll hide it from marketing though. Man looks on the outside, I chuckled to myself... but corporate executives will just have to get used to cold tea.