It keeps surprising me that “you Americans” are still not using the SI system. As an European, it feels like I am reading an article from 1830, with hp instead of kW and lb-ft instead of Nm.
But - out of curiosity - why is the soda can measured in ml and not in fl oz?
I was surprised during NASA's first commentary session of the WEBB telescope launch. It seemed like it was the first time when they were consistently using SI units while speaking to their US audience. I think one time an imperial unit slipped out, but it got corrected immediately.
Imperial units are often tied to measurement devices or operations of a device, than just being a collection of odd standards.
A passenger jet can attempt a landing on a 3000 feet long runway from 4 nautical miles from touchdown point, flying 250 knots at 1500 feet. Altimeters must be calibrated to announced local atmospheric pressure, or the default to 29.92 inHg or 1013 hPa.
Autoclave is a device used for sterilization that exploits saturated(pressure equal to ambient) steam. It is usually ran for 15 minutes at 121C(250F). According to a random internet source[1], atmospheric pressure at sea level is around 15 psi, and 250F is the point where pressure of steam exceeds that, being a function of temperature.
(One of) the beauty of SI units is measurement devices itself are universally built and marked in SI units that disparate measurements across industries can be converted and compared against. There is no “3000 feet runway 4 miles away” in metric, it’s a 1km runway 6.5km away. There is no need to convert between inHg and feet and PSI, or lb-ft and inch-pounds just because F.G. Superman in 1337 who pioneered art of bicycle repairing set measurement and tolerance for a bike frame to be 50 +/- 3.5 inch-yard per fortnight centigrade.
But that requires phenomena to be well studied and measurements clearly defined against SI units, which is a point more industries than we care to admit has reached.
That has to be an aspect of why imperial units persist, despite NASA and cutting edge aerospace are moving away from it, other than there would be a simple matter of gross widespread ignorance.
You mentioned nautical miles. Originally, the nautical mile was defined as 1/60th of a degree of longitude (aka one minute) along the surface of the sea, and so it is a pretty natural unit from a navigational standpoint.
It has since been redefined based on that original definition, as 1852 meters.
So it’s a goofy measure in that it uses base-60, but is otherwise more in the SI family both in terms of original derivation from natural measurements and in terms of its current SI-based definition.
There are other things out there called a “mile” that aren’t imperial, too. Take care when asking for directions in the Norwegian countryside, for example: https://en.m.wikipedia.org/wiki/Scandinavian_mile
Originally, a meter was defined as 1/10,000,000 of the distance between the equator and the North Pole. The circumference of the earth is now 40,075.017 km instead of 40,000 km but it was a pretty good estimate for 1795.
I don't see why you are being downvoted, you are absolutely right. For example you have US Gallons and Imperial Gallons, with the Imperial ones being used in UK not US.
Yep, and those two gallons aren't even remotely close. It's the most annoying thing on car forums, because someone will always say "oh my car gets 30mpg but everyone here says they are getting 40mpg!"
Like, yes, because you haven't established whether they mean US MPG or Imperial MPG.
YES! I always assume ( and very stupid of me ) that it was some regulation with cars and the way they drive between US and UK making some difference in MPG. I never knew the G in mpg was different!
This is one of the illustration with online or even real world discussions where we argue pass each other under the wrong basic assumption.
I didn't seem that way for their online tracker. Every time you visited the website you have to manual switch it back to SI units as the default was not SI.
It's so annoying. They have the screen real-estate to show both units, but for some reason it's like they're trying make a very subtle statement to their international audience. "For Americans only" or something like that.
I can't believe that there were people who actively worked on killing this effort and actually succeeded. Talk about stupidly reactionary.
In general it seems US public policy has suffered since the 70s. There were things like serious efforts for universal health care or metric conversion. These days it's not even imaginable to make a big change in the country.
> The Metre Convention (French: Convention du Mètre), also known as the Treaty of the Metre,[1] is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Ottoman Empire, United States of America, and Venezuela).
Immigration from Latin America and Asia are certainly helping SI in the US. However, there is a loooooong way ahead... And forget about Celsius, this one is nowhere to be seen.
(US here). It kind of helps to think of celsius between 0-100 as “percent of boiling water” for me. Living in one of the hotter parts of the world at the time, being able to say the temperature is 40-50% of the way to boiling water really seems a good objective definition of “too hot.”
Technically 0F is the freezing point of water, just a different type of water.
As a European I find Fahrenheit kind of makes sense on a human scale as 0 and 100 are the upper and lower limits of it being reasonable to be outside. Below 0 is "too cold", above 100 is "too warm" and when it is 50 it is neither warm or cold.
"Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride (a salt)."
It's funny to use that rationalization regarding 0-100 when in reality the rest of the Imperial system is utterly allergic to that sort of scale. 0F and 100F being endpoints for "reasonable" seems a bit of a stretch as well. As a Canadian that's "reasonably cold" and "way too warm".
And why the heck do sockets and drives come in negative powers of 2 such as 1/2", 1/4", 1/8" whereas smaller tolerances come in 1/1000's of an inch? Why not 1/512" and 1/1024" ? This gets into awkward conversions even within the imperial units such as 5/8" into decimal 0.625" instead of something like 640/1024" because of no good reason :-/
Why does it matter though? They're used for different orders of magnitude. I've never understood why people think that having everything in multiples of 1000 (as the metric system does) is an advantage. Yes it's easy to say how many millimetres there are in a kilometer. But when was the last time that came in handy?
That said, I think the US car industry has moved to metric and it is great to not need multiple sets of everything.
What about if it isn't water you are calculating but some other substance? You use a look up table to find the factors - we need to look up a but more in the table, but it isn't a big deal.
Are you serious, they literally just gave you an example lol.
I always hear that argument about "but when will I need it?" If you're using this system then you're always going to use it. It comes up all the time, it's natural so you don't think about it too much.
Does it mean it's better? Well yes, but it doesn't mean other measuring systems aren't good. You don't need it, but you'll want it once you learn it.
The first is a real example from a friend whose drains were blocked during some construction work, where rainfall from his garden was running into his basement during a storm. Would the water reach the electric cables?
The second is obviously relevant for the people responsible for rivers, storm drains, sewers, dams, hydropower and so on. When we start terraforming Venus, we'll need to add the conversion factor for sulphuric acid rain.
The ease is in moving between measurements. How many feet are in 102.3 inches?
Sure I can do the math to calculate it in my head and take a few seconds.
How many meters are in 240cm? Don't need to 'calculate' it the same method. I just move the decimal over. 2.4m...
I say this as an American who finds our use of Imperial pointless. Infact, there is a highway in Arizona that uses metric instead of imperial, as it was a part of our move to metric. (The current measuring and weights system in the United States is based on Metric, we do use it, just converted into another measure)
Every time I need to add or subtract two measurements.
Quick:
What is 2' 3 5/8" plus or minus 1' 2 19/32"?
or
What is 701.7 mm plus or minus 370.7 mm?
Seriously I work with both everyday, and while I grew up with inches & feet and I still intuitively know how deep two feet of snow is better than 61 cm of snow, I'm really starting to hate the US measurements, and use metric whenever I can.
Also, whenever we deal with things from the rest of the world, it becomes a mashup of US and metric measurements.
The US almost converted to metric in the 1970s, but Nixon squashed it, basically on the complaints of what are surely the ancestors of modern US right wing know-nothings who didn't like "foreign" stuff.
Looking at it historically, the fractions made a lot of sense when things were more coarse, and the ability to split things into even sections, 1/2, 1/3, 1/4... was more common.
OTOH, Metric was designed for doing calculations - we already use the decimal system for all other math, so we should design a measuring system to use the same calculation system. It really does work better.
well, a lot of people don't use SAE sockets for serious stuff. Your IKEA chair might have some 9/16ths wrenches - but for cars and other mechanicals its mostly metric.
A few brake lines and some old exhaust bits might be SAE, but by and large vehicles are done with metric.
Personally I like that SAE has fewer sizes... Its frustrating as hell working on cars with a mixmatch of 6mm 7mm and 8mm bolts. oh this is a 15 but a few awkward 16s! Mostly though, cars are pretty standard. European cars seem to be basically - 7mm 8mm (hose clamps and other tiny stuff) 10mm (air filter housings and such where 8mm is to small) 12mm 13mm (misc bolts, intake manifolds, exhaust, almost everything) 15mm 17mm 19mm (these larger ones are basically suspension and other large components)
When communicating in English with the intent to be understood it is wise to include both, putting the conversion in parens. I’m always thankful when Americans include this - otherwise all those feet and pounds and inches and stone are just random numbers to me.
I just remember that 1hp is 754 watts, but lets just call it 750. Another magic conversion that I remember from working on that stuff is that Nm * RPM / 9549 = kW. We never used ft-lbs though.
kW*h is the unit that absolutely kills me. Especially because people will just say "kW". And before long they're talking about "kW*h per day"... Kills me. "What do you people have against James Prescott Joule?!"
The prefixes with Joules get bigger. 1kWh is 3.6MJ. G and T are rare outside data sizes, it's nice if everything can stay in the milli through kilo prefix range.
I'm European and think in horsepower, not kW. Because I was born 40+ yrs ago. So what?
It's basically just a linear conversion of kw = .75 x hp anyway. What's the huge advantage here?
I'm all for metric or SI. But let's not overstate the value please.
Horsepower is not horsepower. American "HP" is not the same as the horsepower (PS, pferdestärke) we use in Europe when we talk about "horsepower".
a kW is always 1000 watt, not 992.3 watts because of course it's a Canadian kW.
That make me curious to look up the Koenigsegg's power. It would seem they are metric horsepower:
>Two common definitions used today are the mechanical horsepower (or imperial horsepower), which is about 745.7 watts and the metric horsepower, which is approximately 735.5 watts.
I guess speaking as a Brit the foreigners just didn't have proper horses.
Computer people speak in Base 2 units because that's how the devices operate at a low level.
After many years and different widths the smallest common unit of exchange evolved to be a power of two: 8 bits are a byte, not 9, 10, 27, 30, etc; though Unicode might have been better off if 32 bits were the base character. However then older systems would have been at least 75% less useful.
Physical addressing units are also binary, because literal address lines (or their virtually latched equivalents on a serial bit-shift register) are used.
ROM, RAM, and correspondingly non-volatile writable storage inherit this basic premise.
So a non-sales computer person speaking 'kilo' or 'mega' or any other SI unit in relation to a computer part means it will hold or be able to transfer at least that many SI units in the quoted units. Everything gets rounded to the nearest useful neighbor. A digital kilo is not 1000, it is 2^10. A digital mega is correspondingly also 2^20. This is very similar to the exponents in SI units.
For that matter, humans have 8 fingers and 2 thumbs. Wouldn't an octal numbering system make more sense? Though for that we'd have to come up with new unit names near 2^3, 2^6, 2^9, etc that don't sound silly.
> For that matter, humans have 8 fingers and 2 thumbs. Wouldn't an octal numbering system make more sense? Though for that we'd have to come up with new unit names near 2^3, 2^6, 2^9, etc that don't sound silly.
Each of the 4 long fingers has 3 phalanges, so an interesting possibility is to use each thumb to count up to 12 on each hand. Given that many ancient units of measurement where base-12, I wonder why we didn't develop base-12 languages.
I've heard that's how merchants used to count in the Mediterranean. However much like QLC and TLC SSDs are more finicky to work and require stricter discipline than simple on/off storage, the same can be said for fingers and is it up or down.
Kibi didn't exist until 1998 (per your link), so anything you read that was written prior to that and for a few years after still has the kilo=1000/1024 ambiguity.
I personally decided to just use them always for clarity and I saw few people around me catch on. Be the change you want to see, especially when it comes to the free minor stuff.
The advantage is not having to remember all those funny constants and being able to do math in your head that actually makes sense?
Or more important, to be able to write an article that the entire planet can just read without 95% of them (everybody outside the US, UK and Myanmar) having to resort to Google to find out if those numbers are impressive or not?
It isn't funny because the GP doesn't want SI units to be used because they are a standard but because 95% of the world can understand them. I'm certain that more than 95% of people understand years.
This sounds like it is directed at me and I don't see why. Humor is often dependent on context. Some jokes are funny in some situations and not in others. The above joke is not funny here since it entirely misses the context in which it should be used.
>The advantage is not having to remember all those funny constants
This, very much! I've done a ton of physical simulation code in my life. Whenever some newb or student comes to me for the first time with their simulation code that mysteriously doesn't work, in 90% of cases they stupidly didn't stick to SI and forked up some unit conversion, or mutiple. I tell the to keep it in SI and never let me see them make that mistake again. (Only exception is simple 1-to-1 unit conversions of parameters and results, when some stupid interface definition demands it that can't easily be changed.)
I think the point was that horsepower is widely understandable and preferred in Europe as a unit of an engine power, despite otherwise using the SI units.
Horsepower is different though, you have imperial horsepower and metric horsepower (and many more). Both are not the same and neither is a round 750 watts.
For the last years I’ve mostly seen watts being used in NL, but it’s been ages since I saw a fast and furious movie or a top gear show. The car sellers use kW and often also, I assume metric, horsepower.
Good addition / correction. So the amount of people that is unable to follow the article without too much effort went down from 95% to 80% of the audience.
1. Everything uses a common base, so you don't get a base change on a scale change (or indeed, two different bases for different parts of the same measurement), and dimensional consistency becomes trivial.
2. The base is base-10, which is the same as our common counting system.
There are two exceptions I’m aware of to “SI is easier in practice”.
1. Temperature. It’s useful to elongate units over the range normally experienced by humans, which Fahrenheit does and Celsius does not, because it avoids tenths of a degree, for example, in room temperature selection.
2. Woodworking and similar: it’s useful to use powers of two because it’s very common to be marking/cutting/etc. 1/2 or 2x a value, which is easier to do in inverse power of two English measurements.
I've found metric to be better for woodworking, and especially metalworking. Powers of two (imperial) are no easier than doubling a metric measurement, and more difficult when partitioning items items in thirds or fourths, or having to cut wood in half with lengths like 56 and 7/32 inches (1428mm).
Same. Screens and wheels are still 100% described in inches in sales.
Cars are specified with HP and optionally kW. Never kW alone.
Outside of these weird exceptions, it's SI all the way. And this doesn't really vary with age. The web site whrere you buy wheels and TVs doesn't know your age so it will say the rims or screens are 20" regardless of who you are.
There's more nuance to it though: if you take a closer look at fields where inch are used even in fully metric language environments you'll find that it's often more a class designation than a measurement. A 21 foot container does not exist (turns out that according to the wiki 20 foot containers aren't even allowed to be 20 foot long, they are 40/2 minus some defined amount of padding)
It's even more pronounced with camera sensors, the size given in fractions of an inch is some kind of "equivalent to", whereas the size in mm is the actual size. Apparently the image sensor inch is 16mm or something like that.
Calories, grit, carats (for diamonds), Beaufort, viscocity is of ten boven in cP, grit (based on inches), dernier, rpm, dpi, lightyears, and of course km/hr. Plenty of non-SI units in use
Yes. I meant metric and sloppily said "SI" despite most common metric units only occasionally being SI.
Beaufort is a dimensionless label as far as I'm aware and grit is used as such too (i.e. it never says anything else than "240" i.e. it doesn't "240 grit" or "240 something per inch").
Grit is based on the amount of particles that fit through an inch square. You could also indicate it with the particle size inmicrometers.
My list wasn't close to exhaustive. We use all kinds of weird units.
Besides bar I sometimes see mmHg for pressure. Shoe sizes. I've never seen acceleration in m/s2 outside a physics problem, otherwise it's either G or seconds to 100 km/hr.
> We use all kinds of weird units.
> Grit is based on the amount of particles that fit through an inch square.
I'm aware. But I'd say its mostly used as a dimensionless. When I argue "we use metric except for these few" I mean in the cases where the unit (a length, mass, pressure etc) is actually uttered or written.
In some cases as you note there are labels which have non-metric definitions underneath, such as sand paper particles having a never-pronounced inch definition. The same goes for some weapon calibers where you might say a ".303 cartrige" for rifle ammunition but you'd never say a ".303 inch cartidge". A lot of people probably use these labels without knowing they are using an imperial definition. And that (I'm guessing) is also part of why it survived the metrification.
> I've never seen acceleration in m/s2 outside a physics problem, otherwise it's either G or seconds to 100 km/hr.
"10s to 100km/h" is as metric as m/s2 though (But again not pure SI).
g being a constant obviously has no explicit unit, it's as metric as you want it to be :) I hear "5g" as 5x9.82m/s2 but an american probably hears something else.
>>As an European, it feels like I am reading an article from 1830, with hp instead of kW
Where in Europe are you that anyone uses kW for engine power lol. Yes it's listed in kW on my registration document but I've literally never heard anyone using kilowatts to describe engine power instead of horsepower, and I lived in a few European countries so far.
I’m in the Netherlands. I just did a Google search for electric cars and checked the top 3 results (Polestar, Hyundai Ionic, Mini) and all three of them list the kW numbers first / large and then the pk number between brackets or small. So we can safely assume that kW is dominant where I am.
If you want to see something fun, go check the size of the tires on your car (printed on the wall of the tire). It will read something like "245/35R18", where 245 is the section width in millimeters and 18 is the diameter in inches. All standard tire sizes use a combination of inches and millimeters, haha.
it gets worse the more you dig in. The middle number is am aspect ratio for length of sidewall. so its side wall thickness 35% of 245mm. Then on top of that when youre getting into trucks and jeeps common sizing switches to inches. so you go from 315/70/R18 to something like 35x12.5r18
Yes, it's funny that when the standard unit is a somewhat lower number (so the KW number is the same magnitude but just a bit lower / less impressive than in HP) there is more resistance to the change.
I think in EU it is mostly due to the German car industry (and all the associated publications) unwilling to change.
In the German speaking world everyone knows what a hp is (PS), how much his car has, his past cars had, in which configurations their car is available... although the kW is what is printed on the documents since ages now.
Nobody likes change. Some people still complain about the Euro, and that the DM was so much better... At least it is not called ECU.
This is so true! Fortunately, for BEV we seem to switch and this works incredibly well. You see kW and you know its about electrics, you see HP (or rather: PS) and you know it's about one of those wonky old "explosions in a tincan" things that eventually displaced the horse. It's quite powerful linguistic era demarcation.
I'd dispute that. Everybody can roughly imagine a 1/4 multitude of the 2.5 kW of a typical hairdryer, nobody has a meaningful mental image of the amount of continuous work one could expect rotating a number horses (peak power per horse is about 15 hp)
But seriously, I do like the split-phase power we have in the US. I think we get the best of both worlds, having lower voltages in most living spaces, and higher voltages reserved for high-power appliances.
>>I think we get the best of both worlds, having lower voltages in most living spaces
How is this possibly a benefit for anything though. It's not like 110V is safer in any practical way, if you stick something in a socket it will kill you just as much as 220V would, so it seems like for literally no reason at all American homes have a much less "ability" to support a wide range of devices that work without any issue elsewhere in the world.
It's safer because of ohms law. Anything you short it with (whether that be an object that might heat up, or a human) will pass half the current and a quarter of the power.
I've been shocked with 120v on bare skin multiple times.
Yes, but my point is that it's still just as deadly for a human. It's like asking whether you want to be in a plane crash going 300mph or 600mph - it doesn't really matter. The #1 improvement in home safety when it comes to the electrical system is the socket design to prevent foreign objects entering(like the British plug design for instance), and second one is a working RCB fuse to kill the power before you even feel a tingle. 110V or 220V doesn't really matter.
Crashing at 300mph is guaranteed deadly. Being shocked with 120v is not. I've been shocked a half-dozen times and I haven't been injured in any way.
Current code in US/Canada also requires RCDs (we call them GFCI) in some places (and AFCI everywhere, which the rest of the world hasn't really adopted) and shuttered outlets... but these do not catch all types of faults. For instance, if a human conducts electricity across two conductors connected to an RCD/GFCI, it won't trip. It only trips if current is drawn to ground or to another circuit. Layered safety is a good approach.
That's not to say that 240v systems are unsafe -- they just have different characteristics and requirements because of it.
Yeah I've been shocked a few times with 240v and it's not nice but doesn't often kill people. Most electricity caused deaths are from something causing a fire rather than shocks I think.
England is a strange combination of metric and imperial. Walking is measured in km but driving is miles. Weight of a person is stone and lbs, but of any other object is in kg and g. Height of a person is ft and inches, but of any object is in m, cm or mm. It's very odd
When my baby was born about a year ago here in UK I would always say his weight in kg when someone asked, and people would literally stare me blank in the face and say they have no idea if that's a lot or not. Once I converted it to pounds for them they were like "oh yeah, he's a big baby then".
Yeah, it's a pain point for me as well. We try to do all of our design work in SI units, use metric screw, etc. The problem is that industry simply isn't aligned this way. Sometimes you end-up with such a mess that you are forced to go back to imperial just for sanity.
The problem with switching the US to the metric system is that the cost would be truly massive. It would take decades, somewhere in the order of 50 years, for a complete conversion.
There's the obvious, things like every single highway sign would have to be replaced. And then there's everything else, like every single tool that everyone owns in this country would have to be replaced at some point. You would still have to be able to buy and use imperial unit hardware and tools for decades during and likely after the transition. I can't possibly list just how deep and wide such a conversion would have to reach.
And that's assuming everyone goes along for the ride. That said, a 50 year timeline would mean a new generation would grow up using the metric system. Another 25 years after that and we should be OK.
All of that said, the real problem is political. The cost of such a transition would be significant. Politicians will only get behind things they can convert into votes. Going metric isn't one of these things. Spending billions of dollars over five decades isn't something anyone can use to win an election. Most people aren't close enough to the design and manufacturing of goods to understand just how much this system actually hurts us. And so, going metric, in a practical sense, becomes an impossible dream.
It's not that great a motor design. It's good, but we had similar power to weight motors where I worked 10 years ago and could run 200kW for more than 20 seconds. Good motor designs are cool, but IMHO they are usually not news-worthy but are just marketing.
The Farenheit temperature scale makes a little bit more sense to me then the Celsius one. It covers the temperatures we care about in more or less temperate climate, with 0°F being the lowest temperatures one will witness (-32C) and 100°F the highest (38°C), the latter being also a body temperature above which one has to worry about.
The Europeans are also still not using the SI system for measuring clothes or shoes. Actually I believe clothes and shoe sizes are a much bigger mess between all the countries in Europe than in the US. It is strange that the bureaucrats of the EU have not tried to a least unify these sizes, let alone using metric units.
> But - out of curiosity - why is the soda can measured in ml and not in fl oz?
The article is written for an American magazine while the pictures are from Koenigsegg directly, which are European; beverages use ml and l to measure contents.
Take a look at the graph, also provided by Koenigsegg, it uses Nm and kW.
I was always tought that the liter was an SI unit, I mean, it's defined in terms of SI units, I know it's not a base unit, but weird that it's singled out as "well, you're technically SI compatible, and you're defined in SI units, but we're not gonna let you be part of the group" :)
It even has an official SI symbol (L), despite not being an SI unit, what?!
SI isn't being used for real in Europe either. Highway speed limits there are always in kilometers per hour, instead of the SI units of meters per second as used for spacecraft. Heh.
Expressing quantities in SI units doesn't require 'base units'. SI prefixes are permitted (milli, micro, kilo, mega...), as are certain exclusions (including minutes, hours, ...).
But - out of curiosity - why is the soda can measured in ml and not in fl oz?