@cjd @freemo it is obviously 300 atmosphere-centimeters-squared.

@cjd Pascal would be the metric unit of pressure, ATM is only used in non-workshop settings...

1.5 cm2 with 200 pascal pressure is 200 / 1.5 = 133 and 1/3 newtons pressure.

@freemo
1. If there are 2 ways to measure pressure, do you concede that different measurements ought to be used depending on the environment ?
2. I find your answer hard to believe given a piston of more surface would exact LESS force with the same pressure...

@cjd

#1 - sort of.. ATM is only used when no calculations need be applied to it, it is not metric, but its useful if you want to know why your ears popped or when dealing with pressure from altitude changes to know your relative pressure.. Its not really a unit like PSI or pascal is, it is a ratio (the ratio of one pressure to another as in the ratio of pressure at one altitude to another altitude).

#2.. You are correct.. I misremembered the unit as N * m^3 it is infact N / m^3.. though that mistake has little to do with the units as the same mistake could just as easily been made on PSI. I literally responded in bed on my cell a few seconds after I woke up, I should have waited till I was up.

@cjd @freemo 3 kN, no calculator.

Assuming 1 ATM is 100 kpa, which is probably off by 1%, but nobody's gonna botger with that without a calculator

@wolf480pl

yea disregard my answer, I replied a few minutes after i work up, wasnt thinking clearly.

@cjd

@cjd @freemo btw. 1.5cm2 sounds like an awfully small piston, 15cm2 would be seem more appropriate for your everyday excavator

@wolf480pl

Its a miniature excavator. 1/10th scale :)

@cjd

@freemo @wolf480pl
That size would be more common with an air piston indeed, but there are probably cases where a small amount of force is required and only full hydraulic pressure is available...

@wolf480pl @freemo
So basically I'm not saying that the metric system is bad, what I'm saying is that trying to force people to standardize on one system is.

* Datacenter people measure in U (4.4cm)
* Oil traders use Barrels (159L)
* Navel and Aeronautic people use Nautical Miles (1.852km)
* Astronomers use Light-year (9460730472580.8km)

Only a bureaucratic busybody could think that everyone should switch to the same unit.

@cjd @freemo ok, but when the systems these people build interface with each other, it's helpful that they can use a common system that both sides understand.

For example, instead of calculating an orbit in light-seconds, then converting that to miles to calculate how much fuel you need in gallons, and then someone calculating the mass of said fuel, etc. it's easier to use metric throughout.

@cjd @freemo s/someone/somehow/

@wolf480pl @cjd @freemo mandatory quote:
"In metric, one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade—which is 1 percent of the difference between its freezing point and its boiling point. An amount of hydrogen weighing the same amount has exactly one mole of atoms in it. Whereas in the American system, the answer to ‘How much energy does it take to boil a room-temperature gallon of water?’ is ‘Go fuck yourself,’ because you can’t directly relate any of those quantities."

TL;DR
It's better when everything go together logically

https://alessandrorossini.org/we-can-put-an-end-to-imperial-units/

@wolf480pl @freemo
Yup, it's a balancing act, on the one hand you want units which are easy to work with in common computations used in that sector of industry, on the other hand you want interoperability.

In practice though, you want to just go along with whatever is being used in the space you're working in, units are political.

@cjd @freemo I'm still not sold on pounds per square inch being any easier to work with than pascals or bars (1 bar = 100kPa ~= 1 ATM).

Also at least one air disaster happened because someone mixed up lbs and kg when calculating airplane fuel

@wolf480pl @freemo
The problem with kPa is a result of the Newton. If instead of Newtons there was just kg-force then anyone who understood what a kg and a cm is (everyone in Europe) would then be able to reason out the measurements of pressure and torque.

@cjd You seem confused...

you said

> If instead of Newtons there was just kg-force

A newton is a unit force, so adding kg into it as kg-force makes no sense. A newton (as any force would be) is mass-acceleration which in this case is the standard kg * m/s^2

So its already in standard units and all nice simple multiples (unlike PSI which becomes quite confusing in any other multiple like feet)

@freemo
Have you ever operated a lathe, milling machine, surface grinder, welder, air compressor, impact wrench, or torque wrench ?

@cjd yes many times both in metric and imperial units. All the ones in the netherlands and europe are exclusively metric of course.

In fact aside from a small global population in the USA virtually the entire world of people who work with such things all do so in metric...

your point?

@cjd You probably dont realize it but doing science tends to require building things, and often those things can be fairly advanced with very critical specifications. A few millimeters off and you wind up with something that doesnt work at all or bad data.

Have you ever built a particle accelerator by hand for example?

@freemo
Before I got into computers I studied Machine Technology, I've used every one of those things I mentioned at least a little. I also replaced a transmission, built a firewood saw, did a fair amount of residential wiring, and my point is that the Metric system is *not bad*, but there are applications where it doesn't make sense.

I've definitely never built a particle accelerator, but if I did you can bet I'd be working with the measurements used in that field.

@cjd Your expiernce is not in question. I was merely pointing out that scienctists that tend to take on personal projects need to work with every single one of those pieces of equipment as well. Building devices is hard to escape in most areas of science and they tend to have demanding specifications.

Thing is, you havent actually given a single reason that the imperial system is better, the few you gave were simply incorrect (like implying that newtons wasnt based on base metric units).. .yet there are quite a few reasons metric is superior (intuitive units that scale by simple powers of 10).

If you could list even one example of how imperial units are easier to work with in any context at all (that doesnt rely on simple familiarity with imperial units itself) then I'd be happy to consider it. But so far there isnt a single advantage mentioned to imperial units of any kind, not a single setting where imperial units are the norm (outside of the USA), and quite a few reasons metric units are suprior.

There is a reason the entire world, except the USA, uses metric units whether its science, woodworking, carpentry, metalwork, lathe, or any other field you can imagine.. because its the better choice in every field except in the USA which for whatever reason prefers to stay in the dark ages when it comes to unit of measurements.

@freemo
Havent actually given a single reason that the imperial system is better <-- All I ever wanted to say is that forcing a system of measurement on people is bad.

If you could list even one example of how imperial units are easier to work with in any context at all <-- I already told you: PSI, foot-pounds (torque) and foot-pounds (work). They are intuitive to anybody who knows two of the most basic units of that system of measures.

@cjd

> I already told you: PSI, foot-pounds (torque) and foot-pounds (work). They are intuitive to anybody who knows two of the most basic units of that system of measures.

Yes but that was trivially debunked... Anyone working with the metric system has equivelant units.. Pascal (pressure), Newton-meters (torque) and Newton-meters (work), which require only knowledge of the two most basic units of the metric system, meters and newtons...

So you havent in any way given why imperial is superior at all.. you just said "if i already know how to work with these really obscure units that no one in the world but me and people near me use then its easier cause im familiar with it"... thats a horrible excuse considering we live in a wider world..

Moreover there ARE disadvantages beyond just familiarity.. the lack of easy to remember prefixes being the most notable which makes the imperial system far far less intuitive when working PSI or foot-pounds at large or small scale, while its trivial to work at large or small scales in the metric equivalent.

so while you did try to make that argument it ultimately failed quite poorly IMO.

Moreover forcing a system of measurement on a people is only bad if its arbitrary, when the new system of measurement is significantly superior, as metric is, then it isnt a bad thing at all. Americans would be better off in the end by far considering they are adopting a system with many advantages and leaving behind a system without a single advantage aside from familiarity (which is temporary).

@freemo
Newtons are not the most basic units of the metric system, a common person only knows kg, cm, meters, km, and L.

On the topic of forcing measurement systems on people, have you read Seeing Like A State by James C. Scott? He speaks a bit about the actual history of the Metric system.

@cjd Everything you said applies just as much to imperial as metric... Newton is no more a basic unit than the pound-force is.. However a newton is a combination of the same units in metric as pound-force is in imperial, except that of course imperial units use convoluted numbers and multiplies where metric does not.

In metric is really simple, a newton is the force it takes to make 1 kg of mass accelerate at 1 m/s^2, nice and easy... not so much with the imperial pound-force. 1 pound-force is equal to the force it takes to accelerate 1 pound by 32.174 ft/s2 (good luck remembering that).. or if you really want to get convoluted 1 ounces (16 ounce-force) by 514.784 ft/sec^2

I think its quite obvious that newtons are far more intuitive and easier to remember than the convoluted pound-force.

@freemo
Everybody in the US knows 1lb mass (from buying food) and 1lb-force is almost the same. A newton would work great if it was almost the same as 1kg, but it's not.

But I think the overarching point here is that forcing people to change their units of measure is, and has always been, an act of colonialism. Historically it has usually been combined with forcing people to change their language and religion.

@cjd A newton is the same idea s a pound-force but applies to kg with simpler numbers.. 10 kg in weight is similar the same force (exerted due to gravity) as 1 newton.. everyone is familiar with it too. the difference is the math is based on simple multiples of 10...

Now ask any random american to calculate something from a pound-force and the numbers are so convoluted even experienced people often cant.. "What if I apply 5 ounce-force to a ton of bricks how fast will it accelerate".. good luck finding a single american who can answer that... however ask "if i apply 5 millinewton to 10 kg of metal how fast will it accelerate", then youc an do the math in your head and most europeans would have little problem doing it if they know even basic math.

Sorry but i am not seeing where the advantage of a pound-force is here at all.

@cjd @freemo isn't 1 newton defined as the weight of 1 kilogram on the surface of the Earth?

@cjd @freemo but, but, what engineer uses atmospheres fo pressure? Or cm's for that matter?

And by what measure are Pascals untintuitive?

@qwazix

SCUBA engineers use ATM for pressure all the time. Though ATM isnt really used professionally too much outside of SCUBA or deep sea engineering.

cm is pretty common though, in fact I cant think of any alternative an engineer is likely to use.

@cjd

@freemo @qwazix @cjd

I've seen ATM decently often in steam power. (I say decently because it's been forever and it was pretty 50/50)

@IAmAWarCrime

Steam power makes sense because the pressure as relative to ambient is ultimately what matters.

ATM is not metric but its also not **really** a unit (well it is but its not really used like one).. and ATM is useful when your working with ratios of ambient pressure where ambient pressure is approximately seal level pressure.

@qwazix @cjd

@freemo @qwazix @cjd

>seal pressure
This makes me smile more than reasonable

@IAmAWarCrime

LOL this has my seal of approval.

@qwazix @cjd