Why not ban AWG

[senso]

PS: NASA uses the metric system.

Of course. The metric system is common in the worldwide scientific community. Outside the scientific community is quite different.

Explain this if NASA uses metric...
http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure

Or was the switch to metric after the ups?

[c4757p]

If you click through to the document they cite, you see this:

The MCO MIB has determined that the root cause for the loss of the MCO spacecraft was the failure to use metric units in the coding of a ground software file, “Small Forces,” used in trajectory models. Specifically, thruster performance data in English units instead of metric units was used in the software application code titled SM_FORCES (small forces).

If I'm reading that correctly, then it was supposed to be in metric, but some programmer improperly used Imperial units in one program.

[madires]

Explain this if NASA uses metric...
http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure

Or was the switch to metric after the ups?

http://www.space.com/3332-nasa-finally-metric.html

[Monkeh]

Pilots use metric, but this can cause confusion if you are not aware of the system in use with regards to the readings. See the Gimli glider for more.

Not for altitude or speed they don't. Feet and knots. (yes, I know knots are scaled to metric units, they're still not kilometres per hour)

How are knots scaled to metric units? Knots are nautical miles per hour, and a nautical mile was based on one minute of longitude at the equator. Where does the metric system come into it?

Because a nautical mile is defined as exactly 1,852 metres.

[AlfBaz]

I seem to recollect hearing that knots came about from the real old days where they would throw a log over the back of the ship with a rope tied to it. The rope had knots tied in it (don't know how far apart) and they would count how many knots passed over a given time. This meant that you could be travelling at a great rate of knots but if you were sailing into a strong current your actual speed, relative to land mass, was a great deal slower

[c4757p]

I seem to recollect hearing that knots came about from the real old days where they would throw a log over the back of the ship with a rope tied to it. The rope had knots tied in it (don't know how far apart) and they would count how many knots passed over a given time.

Not how many passed, how many were above the water, IIRC. More speed = more rope tension = log rises up and exposes more knots.

[westfw]

Imperial A, V, Ohm? That's simple. All you need to do is relate electricity to the hydraulic analogy.

No, no.  It's important in the imperial system that units NOT be related to other units, or at least not in any sensible way.  That would make things too easy during conversion.  (I remind you: 1 mile = 5280 ft !)
So we could start, say, by defining the "imperial farad" as the capacitance of two metal plates with 1 acre of area placed 1 inch apart (in vacuum, of course.)  If I did my math right, that's about 1.4uF, so it's actually a useful magnitude (unlike the NORMAL Farad, which is much too large!)

[c4757p]

Imperial A, V, Ohm? That's simple. All you need to do is relate electricity to the hydraulic analogy.

No, no.  It's important in the imperial system that units NOT be related to other units, or at least not in any sensible way.  That would make things too easy during conversion.

If relating electric potential to water pressure makes conversion easier for you, you are a mathematics, physics and unit conversion wizard!

[AlfBaz]

Not how many passed, how many were above the water, IIRC. More speed = more rope tension = log rises up and exposes more knots.

LOL this from people who though the earth was flat and thought it was trendy to wear a bird on the shoulder

[c4757p]

It actually strikes me as a perfectly good way to measure speed through water, though if you wanted it to be linear you'd need a conversion table...

[AlfBaz]

...and then of course you would have to take water samples if you were sailing near river outlets or polar caps as the water density would change as the salinity changed

[c4757p]

Enough to make a non-negligible difference? Remember, the precision here is "knots on a rope"...

[Rufus]

It actually strikes me as a perfectly good way to measure speed through water, though if you wanted it to be linear you'd need a conversion table...

But they didn't do that. They counted knots in a line paid out from a reel during a period measured by a sand glass.

[dfmischler]

Knots and the Nautical Mile

[c4757p]

But they didn't do that. They counted knots in a line paid out from a reel during a period measured by a sand glass.

That does seem like a better way. I should have clarified that my "IIRC" included "take with a fistful of salt", I heard that from one old pilot who may or may not know anything about things not directly related to aviation.....

[TopLoser]

Plus there is the little complication of tidal flow, are we measuring absolute or relative speed? Quite possible to be doing 20 knots and not making any progress or even going backwards!

[rolycat]

The reason we don't give up the ghost over here can be summed up in one word. Construction! Every building, every plumbing fitting and fixture, every conduit of bulk cable, etc has been based on imperial measures for a couple hundred years. Nothing would work and nothing would fit together properly. It's one thing for say the auto mfg's to change tap sizes and use different bolts. It's another matter entirely when you're talking about 1000 sheets of drywall, $10,000.00 worth of kitchen and bathroom fixtures, reengineering roof trusses, stud spacing on walls, mating up with existing infrastructure, and the list goes on. That's just for one moderately sized house.  Multiply that by maybe 100 million and include industrial/commercial buildings. Now figure in the amount of redundant stock all the contractors and retailers would need to carry.  The costs would run into the trillions if not hundreds of trillions.  With that kind of money on the line nobody is going to change a damn thing over here when we have a system that works fine as is.  I guarantee if you owned a home in the states for 5 years you'd be cursing the metric system in no time flat!

That's not a reason - it's an excuse. The British construction industry, like many others, converted to the metric system without crippling costs. In most cases the conversion was a 'soft' one - the new dimensions were specified in metric, but no physical changes were required. Plasterboard (drywall to Yanks) is now officially 13mm thick, but many builders still call it half-inch.

Americans are just stupidly attached to their old familiar systems, even if they don't make sense. So are Brits, of course. We still use miles on the roads, and woe betide any pub trying to serve beer by the litre instead of the pint.

[AlfBaz]

They have been teaching the metric system here since '72. At school I hardly ever heard of inches, pounds etc. What a shock when I joined the work force...

I use to wonder why old blokes in the construction industry liked to measure things in inches, I thought it was because they were brought up with it but now that I'm over 40 and tape measures still come with inches and millimetres I know the real reason.... The numbers are easier to see in the inch scale

[Phaedrus]

We really just need to redo the whole numerical system. Just scrap the whole lot of it and use dozenal instead.

1
2
3
4
5
6
7
8
9
X = 10
E = 11
10 = 12



Then we can keep the nice power rule found in metric (but in duodecimal), but have the easy divisibility (1,2,3,4,6,12) of imperial! We can even keep the same base units. We just have to redefine the prefixes... And reeducate the whole planet to a different numerical system. 


EDIT: While we're at it we should take the opportunity to fix electrical charge notation so that electrons have a positive charge, and current flow follows the flow of electrons, rather than the reverse of it. This would make a lot of things make more sense. Also, we can rename the Positron to the Negatron, which just sounds cooler.

[Stonent]

I don't mind the metric system, but I really don't like celcius. I feel it isn't fine grained enough to be every day useful.
Yes it makes logical sense but it doesn't seem to make practical sense.

If we really want to do this right, lets just switch to Kelvin and leave it at that.

[AlfBaz]

lets just switch to Kelvin and leave it at that.

unfortunately for you the temperature difference from 1 degree kelvin to the next is still as "grainy" (and the same) as 1 degree celsius to the next

[Phaedrus]

I don't mind the metric system, but I really don't like celcius. I feel it isn't fine grained enough to be every day useful.
Yes it makes logical sense but it doesn't seem to make practical sense.

If we really want to do this right, lets just switch to Kelvin and leave it at that.

Dozenal would fix that as well, because you'd get 144 degrees between freezing and boiling, and the notation would still be 0 - 100! You get more resolution for free.




(I'm joking, by the way)

[edavid]

That's not a reason - it's an excuse. The British construction industry, like many others, converted to the metric system without crippling costs. In most cases the conversion was a 'soft' one - the new dimensions were specified in metric, but no physical changes were required. Plasterboard (drywall to Yanks) is now officially 13mm thick, but many builders still call it half-inch.

What's the point of this kind of soft conversion?  You still need 13mm screws, 13mm plywood, and everything else (and presumably 6mm everything as well).  Why not just continue to measure it in inches?

Americans are just stupidly attached to their old familiar systems, even if they don't make sense. So are Brits, of course. We still use miles on the roads, and woe betide any pub trying to serve beer by the litre instead of the pint.

I don't see where the stupidity comes in.  Why should the US convert, especially as we can see from the British example that there's little benefit?  Don't forget that the US economy is almost as large as Europe's, so we certainly don't have to convert.

[c4757p]

Celsius isn't fine-grained enough for everyday use? Can you honestly feel a 1F difference? I'm hard pressed to discern an 1C difference!

-30C: please kill me
-20C: holy shit it's cold!
-10C: damn, it's chilly today!
0C: snowman weather
10C: light jacket weather
20C: room temperature
30C: pretty warm
35C: damn, it's warm today!
37C: holy shit it's hot!
40C: please kill me

Disclaimer: Opinions vary by region. Just ask someone from northern Canada. But I refuse to believe northern Canadians exist.

Kill Me to Kill Me is a 70 degree spread. Not enough for you?

I've also become quite good at estimating the fives from 45 to 80, a useful range for electronics.

[Stonent]

lets just switch to Kelvin and leave it at that.

unfortunately for you the temperature difference from 1 degree kelvin to the next is still as "grainy" (and the same) as 1 degree celsius to the next

Yeah I know. I just want to mess up both sides.

We could always go to Rankine!