Metrickery

[briantrumpet]

Christ knows why we don't just bite the bullet and 'go metric'.

We've been flopping around on this one for decades.

Imperial measurements are complete codswallop although I still use some as i am an older person and that's what I was taught.

What can be easier than Base 10?

Depends what you're doing with it.

If you forget the mathematics, and think in human terms, the old imperial units have some good points.

Feet/inches and shillings/pennies: 12s make much practical sense, as you can divide them into 2s, 3s, 4s and 6s easily. 10 are rubbish, as you've only got 2s and 5s. Pounds/ounces - using 16 ounces means you can halve six times from a pound and still have a recognised unit (1/4oz), whereas once you start halving kilogrammes, what are the recognised and conceptualisable units? 100g, 50g, 1g? Units based around halving/doubling are so much easier (as evidenced by how music rhythm is conceptualised). Our brains are good at imagining halving, hence 1/2", 1/4", 3/8" (1/4" plus half as much). But we're rubbish at imagining (accurately) a tenth or fifth. If you'e doing something by eye, something based on 12s (for its factors) and halving is much more suited to the way our brains work.

I'll agree that the metric system makes much more mathematical sense, as an integrated system, but I suspect that one of the reasons that many old measurements have stuck around longer than I thought they would is that they suit our brains and perception better. I'd assumed that I would be the last UK generation to be using imperial (it had just been 'fully' adopted when I started school, and there was very much the air of evangelism about it at the time), so I'm still surprised how often young pupils still refer to imperial units.

 

[jefmcg]

I remember arguing with a doctor friend who was bemoaning patients quoting their weight in stone, babies' weight in pounds and so on. I asked her what blood pressure should be and was quoted some arcane figure. So what would that be in Pascals then?

It's millimetres of mercury. It's not an SI unit, I guess, but it's metric.

Or did she use something else?

 

[cardiac case]

Ah ! I know this one.

Pressure is measured in bars.

Too many visits to bars = high blood pressure.

 

[marknotgeorge]

I put it to m'learned friends that as computing power has come on in leaps and bounds since the early 70s, conversion is now a relatively trivial task. Thus as long as both sides of a transaction are clear as to what units are used, metrication doesn't matter as much any more.

 

[SpokeyDokey]

Depends what you're doing with it.

If you forget the mathematics, and think in human terms, the old imperial units have some good points.

Feet/inches and shillings/pennies: 12s make much practical sense, as you can divide them into 2s, 3s, 4s and 6s easily. 10 are rubbish, as you've only got 2s and 5s. Pounds/ounces - using 16 ounces means you can halve six times from a pound and still have a recognised unit (1/4oz), whereas once you start halving kilogrammes, what are the recognised and conceptualisable units? 100g, 50g, 1g? Units based around halving/doubling are so much easier (as evidenced by how music rhythm is conceptualised). Our brains are good at imagining halving, hence 1/2", 1/4", 3/8" (1/4" plus half as much). But we're rubbish at imagining (accurately) a tenth or fifth. If you'e doing something by eye, something based on 12s (for its factors) and halving is much more suited to the way our brains work.

I'll agree that the metric system makes much more mathematical sense, as an integrated system, but I suspect that one of the reasons that many old measurements have stuck around longer than I thought they would is that they suit our brains and perception better. I'd assumed that I would be the last UK generation to be using imperial (it had just been 'fully' adopted when I started school, and there was very much the air of evangelism about it at the time), so I'm still surprised how often young pupils still refer to imperial units.

I hear what you are saying but at the end of the day the wheels haven't fallen off the Money Bus since we got rid of threepenny bits etc.

 

[Profpointy]

It's all very well saying metric for everything, but if we want a half-inch bolt, are we really supposed to call it a 12.7mm?
Bear in mind proper scientists use a whole mish-mash of units. Astronomers tend to use light-years not metres, and their Cosmologists cousins will use Parsecs not light years. How about Hubble's law, usually quoted as so many kilometres per second per megaparsec - which is a hotch-potch of a measure using two different units for the same thing. Atomic physicists will quote masses (and energies) in electron volts - a non-metric unit (of energy).

And a foot is such a convenient unit, being the distance light goes in a nanosecond.

And pity the poor electrical student faced with two differently defined sets of (metric) units - one based on cgs (centimetres, grammes, seconds) and the other based on SI (metres, kilogrammes, seconds) - and ends up with conversion factors involving multiples of pi .

Basically you need to know and use what's convenient (or historic) for any given field. And you need to know the old stuff to understand old equipment or books.

And anyway, why teach cm in schools - (almost) no-one uses centimetres in the real world these days.

 

[briantrumpet]

i hear what you are saying but at the end of the day the wheels haven't fallen off the Money Bus since we got rid of threepenny bits etc.

This is true, but I think that in the money stakes the ease of calculation actually is more important than being able to divide into 2s, 3s, 4s and 6s. The maths of 12 pennies to a shilling, twenty shillings to a pound (and 21 to a guinea) isn't a price worth paying for the factorisation properties.

However, having units based round halving/doubling for weights and measures at the household scale does help to explain their persistence, I think. That's all. Rather boring, I know.

 

[swansonj]

It's all very well saying metric for everything, but if we want a half-inch bolt, are we really supposed to call it a 12.7mm?
Bear in mind proper scientists use a whole mish-mash of units. Astronomers tend to use light-years not metres, and their Cosmologists cousins will use Parsecs not light years. How about Hubble's law, usually quoted as so many kilometres per second per megaparsec - which is a hotch-potch of a measure using two different units for the same thing. Atomic physicists will quote masses (and energies) in electron volts - a non-metric unit (of energy).

And a foot is such a convenient unit, being the distance light goes in a nanosecond.

And pity the poor electrical student faced with two differently defined sets of (metric) units - one based on cgs (centimetres, grammes, seconds) and the other based on SI (metres, kilogrammes, seconds) - and ends up with conversion factors involving multiples of pi .

Basically you need to know and use what's convenient (or historic) for any given field. And you need to know the old stuff to understand old equipment or books.

And anyway, why teach cm in schools - (almost) no-one uses centimetres in the real world these days.

Personally I find deciding I need an M8 bolt easier that a 3/8" - and an M4 is a lot easier than a 4BA or whatever the equivalent is.

 

[fatblokish]

My bike, and its rider, weigh increasing less as we ascend slopes. Where can I buy bathroom scales that measure Newtons?

 

[classic33]

My bike, and its rider, weigh increasing less as we ascend slopes. Where can I buy bathroom scales that measure Newtons?

These?
http://www.alibaba.com/product-detail/Personal-Scale_508045388.html?s=p

 

[BrumJim]

It's all very well saying metric for everything, but if we want a half-inch bolt, are we really supposed to call it a 12.7mm?

Chances are a 10mm bolt will be adequate.

 

[Profpointy]

Chances are a 10mm bolt will be adequate.

won't it rattle around in the hole and the thread won't fit

 

[Pumpkin the robot]

Which thread would you use? Imperial is that bad that they cant even decide on a standard thread system. At least with metric, the thread form is the same it is only the pitch that changes and everyone knows that a 12mm bolt would be a closer size to 1/2" rather than 10mm.

 

[BrumJim]

won't it rattle around in the hole and the thread won't fit

Ah, half-inch diameter. You didn't make it clear if you were talking about shank length or diameter. Which you would have done if you had said: "M12".

 

[Profpointy]

Ah, half-inch diameter. You didn't make it clear if you were talking about shank length or diameter. Which you would have done if you had said: "M12".

one always means diameter surely?

Mind you, I have myself made the faux pas at a car spares shop talking about "half-inch bolt" meaning spanner size hence presumably bolt was 1/4" unc or whatever it was.

and anyway M12 - would that be coarse or fine?