For example we also say it’s 20 degrees celsius outside. And that’s not the proper SI unit either
Can you elaborate on this? As an American without much experience with the SI system, I wouldn’t think twice if someone said this to me
Comment on Why a ton, and not a megagram?
rufus@discuss.tchncs.de 1 year ago
I think it’s written ‘tonne’. And you should call it metric tonne if it’s not clear from the context.
Wikipedia says:
The tonne is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton (United States customary units) and the long ton (British imperial units). The official SI unit is the megagram (symbol: Mg), a less common way to express the same amount.
PP_BOY_@lemmy.world 1 year ago
Krukenberg@feddit.ch 1 year ago
The SI unit for temperature is Kelvin
rufus@discuss.tchncs.de 1 year ago
What would you like to know? Regarding temperatures: ‘Kelvin’ is the proper SI unit. It starts with 0 at absolute zero. And then uses the same size for units as celsius uses. So 0°C (the point at which ice made from water melts) is 273.15 Kelvin. 20°C about where you’d wear a t-shirt is about 293 K. So we don’t say it that way but keep saying it’s 15 or 30°C outside.
Scientists do it right. When you’re melting metal or talking about the temperature of the sun, you won’t have small numbers anyways and you won’t use celsius. You can translate it easily, anyways. Just add and substract the 273.15. You don’t need a formula and a calculator like when you translate between farenheit and celsius.
force@lemmy.world 9 months ago
Actually since 2019 the Celsius is defined directly based off of the Kelvin by the SI
ProvokedGamer@lemmy.ca 1 year ago
Wait, what’s the correct SI unit for 20 degrees Celsius then? I’ve never heard anything besides that.
supercriticalcheese@feddit.it 1 year ago
It’s typically shortened as t.
Normally it’s clear from the context and what units you are using so there is no ambiguity.
rufus@discuss.tchncs.de 1 year ago
I’m not so sure. But maybe you’re right. I thing I was confusing that with tonnage of a ship. But that’s a whole other concept and you can’t really confuse the two.
With the 1000 t thats only because kg is a stupid SI unit and leads to the whole debacle. If there wasn’t a prefix in the unit name itself, I think people would have started to use the SI unit prefixes correctly at some point instead of inventing and omitting other names to compensate.
I think I’ve heard things like megatonne. For example you can say your nuclear bomb has X megaton tnt equivalent.
supercriticalcheese@feddit.it 1 year ago
The official definition of a 1,000 kg is Mg but it’s not very frequently used in practice. Mostly because use of metric tonnes was already diffused
Keep in mind that there is more than just SI units used in Europe in the past. For example if you read through an old thermodynamics textbook in Italian it is likely to use a lot calories and often the CGS system (centimeter grams second and calories).
rufus@discuss.tchncs.de 1 year ago
Sure. I’ve grown up with that stuff. And we also get our weather forecast in celsius each day. You don’t even have to open an old textbook for that.
Ziggurat@sh.itjust.works 1 year ago
For the pleasure to be pedantic, the proper CGS energy unit is the erg, not calorie.
But indeed, even in France, home of the metric, you’ll find people using some customary unit (Calories, or pounds) and even some US units like inches for computer-screen and feet for powered airplanes altitude, and then a shit ton of approximation
Vlyn@lemmy.zip 1 year ago
But it literally is a kiloton? Mostly getting used for explosives if you talk about it, but it’s used:
The reason megagram isn’t used much is because it would be shortened to mg. Which is usually milligram. Sure, you could go the “Mg” route compared to “mg”, but that sucks. So “t” for ton works well. It’s just another name though, it doesn’t matter.
rufus@discuss.tchncs.de 1 year ago
Yeah, I know. But you have the problem with the letter ‘m’ everytime. You just have to pay attention and write it correctly. And there is also ‘micro-’ in addition to the ‘milli’ and ‘mega’ you mentioned. However, most of the time it’s unlikely you’re off by a factor of 1 billion and won’t notice. Just do it right: 'µ, ‘m’, ‘M’.
If you listen to my school teacher, you’re not supposed to use SI prefixes with other things. I think that’s not true but would apply to the ‘kiloton’. People wouldn’t like me talking about a ‘kilo-foot’ or ‘milli-yard’. I’ve had 3 deca-spoons of soup or there were 2.5 kilo-people at the concert.
supercriticalcheese@feddit.it 1 year ago
I think it’s mostly down to the fact the units could be mixed when written down.
Mg and mg should not create confusion in theory the standard milion prefix in metric is a capital M.
Treczoks@lemmy.world 1 year ago
The good thing: All of them are correct. The SI system actually does not care if you throw around extra zeros, so 1000t is fine. It is actually better to stay in the same SI prefix and just use larger numbers to make list entries easier comparable. Just imagine some ship shop would list it’s smaller offers in Mg and then switch to Gg for larger ships.
rufus@discuss.tchncs.de 1 year ago
Hmm, halfway…
If you take the context away: When you learn that in school, it’s marked as a mistake if you write 10 000m. You should have converted that into 10km to get a perfect score.
But there are certainly contexts where it makes sense to stay with one prefix. For example if you write things into a table.
I’m not sure if it’s necessarily the case for comparing stuff… It’s kind of rare that you have things that are a factor of 10000 or a million apart, so it’s kind of difficult for me to find examples. But I have capacitors that are 470uF or 22pF and resistors that are 220 Ohm or a Mega-Ohm or 150kOhm. I know how to handle that and switch between all of them. So people do switch and that’s kind of the point of having those prefixes. If I type it into my calculator I simply use the key to type it in in scientific notation and once again so it gives me the closest power of ten. I forgot the name of that key. ‘E’ or ‘ENG’.