Metric Paper [video]
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The decimeter (i.e. 10cm; ⅒ of a meter) has been hiding in plain sight and fits the bill adequately. It is, however, awkward to communicate. It's about the same width as the width across an average adult's hand, so let's rebrand the decimeter as the "metric hand", or just "hand" in informal contexts.
Conveniently, there are approximately 3 metric hands in 1 foot. The error, 1.6mm per hand, is negligible, and in instances where accuracy and/or precision is at a premium you can rest safe knowing that it really does accumulate at 1.6mm per hand exactly, and not some intractable quantity like the one that comes up with approximating 1 kg as 2.2 lbs.
Previously: <https://news.ycombinator.com/item?id=28455838>
As you say, it's a human scale measure. If you're getting the tape measure out, just use cm and metres.
The point is that people who get paid to use tape measures do measure things in feet and inches and aren't "just us[ing]" centimeters and meters instead. The proliferation of the metric hand would help with this, since it sidesteps the downside to centimeters and meters I've described.
Settling on centimeters as a common unit and neglecting the decimeter is quite odd on its own.
To me they're units that you can eyeball. Units that don't inherently have to be accurate.
If you want accuracy you can use a different metric. If the newspaper described something in terms of football pitches, that doesn't preclude giving the the actual area also.
So I don't see the problem of keeping the foot (~30cm) and using actual metric for the base.
>Settling on centimeters as a common unit and neglecting the decimeter is quite odd on its own.
Well every industry that that im aware of uses mm over cm. Building material is commonly sold in 2400mm heights, more commonly than even 2.4m and if there's an industry that needed the decimetre surely it's the building industry, but even they went the other way and settled on mm.
"'human-scale' objects i.e. those that you are likely to find yourself using your hands to work with"
And I'd say that it's clear enough from context that what I'm taking about is basically "whatever people in the US use inches and feet for (or a large part of that set, at least)". Again, that's the whole point of this thread—things that people continue to use feet for and how it impacts the adoption (or lack thereof) of metric units.
> If you want accuracy you can use a different metric.
"The point is that people [...] aren't"
> I don't see the problem of keeping the foot (~30cm) and using actual metric for the base.
The foot is not a metric unit, full stop.
> Well every industry that that im aware of uses mm over cm
How tall are you? Is that something you answer by reporting it in millimeters?
You're also ignoring the part about how centimeters are not an opportune unit for the types of things I'm describing due to their scale. That makes millimeters even less so.
>How tall are you? Is that something you answer by reporting it in millimeters?
I wouldn't describe a human as something I would use my hands to work with.
Anyway if you asked my height I would say 6ft. If I actually measured myself eg for a BMI I would use cm or mm ~180cm ~1800mm neither of those are hard.
I don't really get why you're arguing against me on this. I know both units. Inches and feet are useful for some things, and I use them for the things I find useful.
I could have the opposite discussion with someone who only uses metric, that imperial is useless because it doesn't do X and they can't imagine ever using it until their imagined use case is fixed. Ultimately it's what you're used to. But if you want the human scale units then imperial is there.
Or just use millimetres.
This document goes over the arguments for cm versus mm, and generally argues that mm/m/km will work for most situations:
> ◊ 4 core units - metre, litre, gram, and tonne;
> ◊ 2 prefixes using the same conversion factor - milli meaning 1/1000th and kilo meaning 1000 X; and
> ◊ 2 concepts - square metres and cubic metres.
> In Australia metrication has been most successful in the areas where we used millimetres. Metrication programs using millimetres have been fast, smooth, and so economical that many individuals and companies have profited from the change.
> Metric conversion has been least successful where centimetres were chosen as the small unit for everyday use. Metric programs using centimetres have been painfully slow, characterised by bitter internal squabbling, and expensive. Failed attempts at metric conversion all have this one thing in common — they tried to introduce the metric system using centimetres.
* http://www.metricationmatters.com/docs/centimetresORmillimet...
It also keeps things 'clean' with consistent 10^3 jumps (also with g/kg/t(onne), mL/L/cu. m).
> One rather startling fact about the Australian metric conversion is that nearly all of their industries opted for the millimeter as their preferred unit of measure, including the construction industry. The plans for Australian houses are drawn up in millimeters. Why use something as small as a millimeter to design something as large as a house? Because decimal numbers are eliminated from the blueprints. Which means that the guy on the job site running the radial arm saw never has to deal with anything but whole numbers. Which means that he makes fewer mistakes. Which means that waste is greatly reduced.
> Actually, no centi-anything. Also, no deci-anything, no deca-anything, and no hecto-anything. […] Drop these four prefixes, and there are only two remaining that non-technical people will ever have to deal with commonly: kilo for thousands, and milli for thousandths. Conversions between measurements become almost unnecessary, and on the rare occasions when they do crop up, there is one and only one conversion factor to remember: 1000.
* https://themetricmaven.com/naughtins-laws/
If you're (e.g.) a machinist and need smaller, there's µm, another 10^3 jump; if a chemist, mg.
Cm will never die out though. Schools (certainly primary) are all cm and m. Plus 1cm3 of water is 1g
Both of these are just as easy to remember.
ft/ns and ft/ms seem pretty useless to me. I guess they work for room-sized things, but go outside and you're converting to miles anyway.
The simplicity of remembering 1 foot is utterly drowned out by trying to appreciate what a nano second is.
As a factoid it's easier to remember yes. But a factoid in isolation is useless. So unless you're going to do E=MC2 in imperial
I'm not sure if "hand" can catch on anymore; how about maybe "deci", pronounced as "desi"?
Building work is all millimeters - no decimal points and it scales well for fifteen foot (hah!) long wall units with shelves and doors down to the thickness of a saw cut.
3200mm is 3.2 metres (close to 10 and half feet) and gets thrown about in a work shop as "thirty two hundred".
Working in mm ( mills ) in building and workshops is a single unit solution with no decimal points and no confusion when chalking numbers on a wall or bit of sheetrock | paper | wood, etc - it's all mills.
As for the kilometre, that's pretty formal, mostly it's just 'K' as in "it's about 20 Kay down the road".
"clicks" gets used .. but we're lazy and K is shorter still.
Star Size Comparison 3 (Vortex) is incredible.
Also like these two, the book is available to view online: http://www.vendian.org/mncharity/cosmicview/
In practice regular paper has ~80g/m^2, meaning 5 grams per sheet, meaning a ream of 500 sheets has exactly 2.5 kg.
In addition to A series, there is also B series (and C series). They all have the same aspect ratio √2
B0 is 1 metre wide, while A0 is 1 meter long. The area of B series sheets is the geometric mean of successive A series sheets. Many books are printed in size B5. When you fold A4 it fits neatly between the pages.
Letter written on A4 paper fits inside a C4 envelope, and both A4 paper and C4 envelope fit inside a B4 envelope.
That doesn't sound right, as A0 is 1 square meter, and it isn't square.
An A0 sheet has an area of 1m².
For the ratio in general, see https://en.wikipedia.org/wiki/Square_root_of_2
A(n) paper is 2^((1/2-n)/2) * 2^((-1/2-n)/2) meters, with an area of 2^-n meters^2
A0 is thus 2^(1/4) meters x 2^(-1/4) meters
MacBooks have always been 16:10. And recently, 16:10 appears to be making a resurgence once again—many notebook models that were 16:9 1080p have moved to WQXGA 2560 × 1600.