Re: Out of Character 9
Actually, a hectare (hundred ares) isn't a nice SI unit at all. SI units keep their powers of 10 in multiples of three -- kilo, mega, milli, micro, nano, etc. -- and anyway, it would have to be based on a square meter rather than a 10 m square (who came up with the are, anyway, and what were they thinking?).
So, for SI, area is either square meters, or square kilometers. Grams are fine, but the naming is screwed up (due to a couple centuries of tradition before scientists and engineers decided metric was almost as screwed up as English traditional and US Customary). The gram is the one that should have weighed 2.205 lb, and we should be measuring aspirin in micrograms and LSD in nanograms. But the kilogram was called that even when it first became the standard, based on an exemplar stored in Paris since the 18th century, so we're stuck with it.
Oh, and the US is partially metric for electricity and energy -- we use coulombs, amps, volts, and watts in electronic measurement and design -- but then instead of Joules (one Watt-second), we use kilowatt-hours to sell electricity, and jump over to horsepower and foot-pounds for mechanical power and energy (I guess a 500 horsepower, 429 cubic inch V-8 is more romantic than a 7.1 liter, 670 kW engine under the hood). Just to confuse things, we also use foot-pounds (or inch-pounds, or inch-ounces) for torque, though SI is just as bad, using Newton-meters for both energy (work) and torque.
And don't even start on units like viscosity -- a centipoise is conveniently sized, but it's also a BUNCH easier to say or write than the SI unit, which I've actually forgotten (we didn't do much with viscosity before I dropped out of college).
Suffice to say, if you want engineering and science not to be nightmares to study and work in, you need to pick one unit system and stick with it, and SI is the easiest one to work in. Now if only we'd defined the meter so gravity was exactly 10.0 m/s^2 at Earth's surface...