5 ms·
Funny how 'km' has become so commonplace we forget we can write '1 Mm' (megameter).
by notjustanymike 5y ago
Funny how 'km' has become so commonplace we forget we can write '1 Mm' (megameter).
- DrBazza 5y agoYou can always convert to brontosaurusii - so this car has a range of 45,495 of them... https://www.theregister.com/Design/page/reg-standards-converter.html https://www.theregister.com/Design/page/reg-standards-conver...
- cogman10 5y agoI see this happen all over the place. Instead of 1 Mg, you'll see thinks like 1000 kg. I think power is the only metric unit I've seen where the common unit also often follows metric notations. 1 kW, MW, GW, TW.
- pwdisswordfish0 5y ago> Instead of 1 Mg, you'll see thinks like 1000 kg. Yeah, I do this a ton myself. I apologize.
- BrandoElFollito 5y agokg is the base SI unit, so 1000 kg is more natural than 1 Mg. The fact that kg is the base unit does not make much sense except for historical reasons when the choice was made. A very bad choice if you ask me.
- Ekaros 5y agoI blame the French... We could have had it all properly and use grave... But no, too big... One of the few ugly bits of SI system. In general otherwise it all just works together so nicely. Then again it's not only weird unit we have, dB is the other one. Ofc, units are nicer to handle, but still... Not that bell isn't weird unit anyway.
- Y_Y 5y agoI agree that bel is a weird unit. To be fair, it's not "in" SI, but just "accepted for use with". I'd also argue that candela and mole are weird for other reasons, and they're SI for real.
- BrandoElFollito 5y agoThe mole is I think for historical reasons, to not piss off chemists too much.
- BrandoElFollito 5y agoI did not know that we were, again, to blame. But at least we have the one and only official and beautiful kilogramme and meter prototype in Sèvres, near Paris. And, again the French way, it is not possible to see them!
- nybble41 5y agoThey may call the kilogram the base unit, but in practice no one talks about millikilograms (just "grams") or microkilograms (just "milligrams"). The gram might be formally defined in terms of a 1 kg physical mass, but for the purpose of SI prefixes the gram is the real base unit and there is nothing wrong with saying 1 Mg instead of 1000 kg.
- BrandoElFollito 5y agoAlso nobody says 1 kilokilogramme (1000 kg). This isaid, the mass base unit in SI is really the kg, even if g would be natural (and indeed people will say 1 g instead of 1 millikilogram). I was always annoyed by kg being the base unit (and I had to drag this suffering throughout my PhD in physics) but this thread opened my eyes on the possibility to use "compensating" prefixes on the kg (millikilogram to say gram) - it is a shame I did not think about that before to drive everyone crazy :)
- laputan_machine 5y agoFrequency too seems to follow the metric convention (e.g. Hz, MHz, GHz, ...)
- leshenka 5y agoAnd don't forget about (kilo)calories mess.
- _Microft 5y ago> I think power is the only metric unit I've seen where the common unit also often follows metric notations. 1 kW, MW, GW, TW. You might just not recognize them as such. Ampere, Volt, Ohm, Tesla, Newton, Pascal, Hertz, Joule, ... are all SI units or directly derived from SI units and used with SI-prefixes regularily.
- chrisseaton 5y agoI see 100cl a lot - bizarre.
- weego 5y agoJust don't edit 1000km to 1kkm and we're golden.
- _Microft 5y agoKilometer works fine for everyday purposes, from fractions of it to orders of magnitude larger, i.e. both 0.1km and 7230km are understandable. Once you are in the realm of science and engineering, you are more likely to encounter scientific notation anyways, e.g. 2.99 x 10^8 m instead of 299 Mm.
- gruez 5y ago...or all the powerbanks that advertise “20,000mAh” rather than just “20Ah”.
- maccard 5y agoPowerbanks are rated that way because batteries are rated that way. For phones it _kind of_ makes sense, as the capacities are closer to the 2.8-3.5 Ah range, and that difference is fairly substantial. (No comment on why processors are measured in GHz rather than MHz). If you want to pick a gripe why do we measure capacity in charge per unit of time times hour, rather than MJ?
- formerly_proven 5y agoThey're marketed that way because big numbers sound good. Lead acid batteries are generally rated in Ah, even if it's just a small stand-by battery with 1.2 Ah. On the other hand, ratings within a group of products are usually done without a prefix change. Perhaps because of defective sorting algorithms, which would e.g. place a 1.7 kV device at the end of the list, while putting a 1500 V device first. That's probably why you see e.g. 4700 µF instead of 4.7 mF as well, though sometimes the latter is used. > If you want to pick a gripe why do we measure capacity in charge per unit of time times hour, rather than MJ? They're equivalent, it's just that writing Wh makes it very clear that you can divide this figure by some discharge power and get the approximate discharge duration. OTOH, an EE likely knows [power W] * [time s] = [energy J] anyway.
- nybble41 5y agoListing capacity in Wh rather than MJ is fine, but many batteries are rated in amp-hours which isn't very helpful unless you also know the voltage. This is particularly annoying when it comes to "smart batteries" such as this USB power pack[0] where you have specs listing "10000 mAh" and "5 volts", but the actual capacity is around 37 Wh because they measured amp-hours at the internal battery and the battery voltage isn't exposed to the user. (Yes, the product description halfway down the page does say "10000mAh/3.7V" in small print if you know to go looking for it, but this isn't noted anywhere in the title or the "About this item" section at the top.) [0] Example: https://www.amazon.com/10000mAh-Portable-Charger-Stylish-Compact/dp/B08D9J2NJP/ https://www.amazon.com/10000mAh-Portable-Charger-Stylish-Com...
- sonium 5y agoThis is nothing compared to how the car industry measures computational power: kDMIPS, kilo-Dhrystone-Mega-instructions-per-second