Saturday, August 18, 2007

Caffeine

The doctor gave me a routine that included "Drink x glasses of water a day. Caffeinated drinks don't count toward your requirement." The instructions did not say "avoid caffeine," only caffeine-containing drinks don't count.

Why Is It?

By this criterion, drinking a litre of iced tea (150 mg caffeine after the ice melts) is evil but drinking a mug of coffee (133 mg caffeine) chased by 3/4 litre of is water acceptable.

I have always assumed that whatever nutrients I ate over a short period became effectively integrated into a single dosage in my body.

References:
Caffeine table from the Center for Science in the Public Interest.
(c) 2007 Bill Barnes

Sunday, August 12, 2007

More information than I need

My bicycle computer can display the miles I've ridden down to one thousandth of a mile (23.001). But wait a minute. The technology* it uses to measure distance can't measure less than about 7 feet and one thousandth of a mile is about 5-1/4 feet.

So, why do they bother with that last decimal place? I know, the answer is "because they can". The display is wide enough and they want to pretend that they are more accurate than they actually are. But wouldn't it be more honest just to leave it off. I know there's always a rounding error but this seems to gratuitously imply it knows more than it does.

* A bicycle computer measures distance by counting the revolutions of the wheel. Every time a magnet attached to a spoke passes a sensor on the fork, it counts "one". Then the electronics, knowing the distance covered in one revolution of the wheel is PI*diameter, converts revolutions to miles or kilometers. Of course, the computer can be calibrated for different wheel sizes and .001 mi would almost be accurate for a 20" child's bike.

(c) 2007 Bill
More like this: http://numbersforeveryone.blogspot.com/