4 ms·
> base-10 numbering system Having decimal numbers, it’s the best solution. Otherwise you’re bound to make mistakes scaling things up or down. > a liter is not
by kergonath 1y ago
> base-10 numbering system
Having decimal numbers, it’s the best solution. Otherwise you’re bound to make mistakes scaling things up or down.
> a liter is not a cubic meter
Well, it’s a dm^3, close enough ;)
Conversion is trivial, 1 m^3 is 1000 l.
A cubic metre is a bit large for everyday use, but it makes sense e.g. when measuring water consumption or larger volumes. The litre also had the advantage of being close to 2 pints, so it already made sense as a unit when it was introduced. Contrary to hours with 100s.
> 'kilogram' is the base unit, not 'gram'
Yeah, this one is perplexing. It’s an annoying inconsistency on an otherwise beautifully regular system.
- GlobalFrog 1y agoI don't understand your issue between gram and kilo gram: gram is the base unit and the prefix kilo, meaning one thousand just says that 1 kg = 1000 grams. It is exactly the same as meters and kilometers: meters is the base unit and 1 km = 1000 meters.
- tokai 1y agoI think they mean that the gram is defined as 1/1000 of a kilogram. With a kilogram having a definition based on physical constants.
- jabl 1y agoThe kilogram is no longer defined by a physical artifact, fwiw. Anyway, the point is the inconsistency in the system due to the kilogram being the base unit. So derived units are defined in terms of kilogram rather than gram. Say, the unit of force, Newton (N), is defined as kgm/s^2 and not gm/s^2). Or pressure, Pascal (Pa) which is N/m^2 which inherits N being defined in terms of the kilogram). And so on. Anyway, an annoying inconsistency maybe but doesn't really affect usage of the system once you get used to it.
- DavidSJ 1y agoIn SI, kg is the base unit, and g is a derived unit.
- selkin 1y agoIt’s an historical artifact, as it was easier to manufacture a reference kilogram than a reference gram. Considering today we set the kilogram by fixing the Planck constant and deriving it from there, we can just divide each side of the definition by 1000 and use that as a base unit. Using kg as the base unit is completely arbitrary, as we can derive each unit of weight directly from the meter and the second, not from the base unit.
- mmooss 1y agoWhy not call the thing that weighs ~2.2 pounds a 'gram'?
- selkin 1y agoFor the same reason it was not renamed "Wug".
- mmooss 1y agoIt's not the same reason. Gram is already part of the nomenclature, wug is not. The change I asked about would shift the relation of the prefixes to the masses: kilogram would represent a mass 1,000 times larger than it does now.
- selkin 1y agoIt's exactly the same reason: gram referenced a known quantity. Changing it by a few insignificant digits because of the kilogram update wouldn't force people to realign their perception of it. Changing it to ~1,000 times what it used to be, or giving it a new name, would force people to realign. There's reason many people still prefer customary and imperial units, and it's not just bigotry and nationalism (even if they play a part in that preference).
- ahartmetz 1y agoReportedly, the kg was going to be called "grav", but it sounded too similar to "Graf", a German feudal rank, and these guys really hated feudalism.