Temperature Conversion
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@Gurth said in Temperature Conversion:
Do any consumers make this kind of calculation on a regular basis?
Yes.
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@Gąska said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@Benjamin-Hall It's like those people who say "If you weigh 60 kilograms on Earth you'd weigh only 10 kilograms on the moon". It makes no sense because kilograms are a unit of mass, not force.
Kilogram-force is a non-standard unit and is classified in SI Metric System as a unit that is unacceptable for use with SI.[4]
@Gurth said in Temperature Conversion:
imagine if we expressed volumes of milk in m·m·m
Don't farmers get paid for it per kilogram?
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Quick question: in the US system of customary units, is
powerenergy usage measured in foot-pounds/minute hours or horsepower-hours or what?
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@mott555 said in Temperature Conversion:
Current: Imagine a cubic parsec packed so tightly with electrons that electron degeneracy pressure prevents it from being any denser. But let's also pretend gravity doesn't exist so it doesn't turn into a black hole and inconvenience us. The number of electrons in that region becomes the base unit of charge, and so current is the number of those passing past a point per unit of time.
Since this is many orders of magnitude worse than this, it sounds like you're building a universe destruction device.
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@PleegWat said in Temperature Conversion:
@Gąska said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@Benjamin-Hall It's like those people who say "If you weigh 60 kilograms on Earth you'd weigh only 10 kilograms on the moon". It makes no sense because kilograms are a unit of mass, not force.
Kilogram-force is a non-standard unit and is classified in SI Metric System as a unit that is unacceptable for use with SI.[4]
Should people stop using atmospheres, calories and carats as well? Because the cited source for that statement lists them as unacceptable as well.
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@Gurth said in Temperature Conversion:
It's the same reason why we're using liters and not m³ for denotating volumes of liquids. It's simply grounded in everyday units.
I don’t think that’s a valid comparison. The litre is technically unnecessary, true, but it has a name of its own like, say, the newton or the volt, not a compound name like kilowatt-hour. Convenience names tend to be there to simplify things — imagine if we expressed volumes of milk in m·m·m — yet kWh does pretty much the opposite.
"The amount of energy my 1000-watt microwave will consume if I run it for an hour." Pretty convenient.
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@Gurth said in Temperature Conversion:
imagine if we expressed volumes of milk in m·m·m
Where "m.m.m" is pronounced like a cow mooing.
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@topspin said in Temperature Conversion:
Do you actually display temperature differences to the customer?
Also, yes.
Now that Johnny found out that his calculations don't make sense, he came up with an ingenious solution: he invented a new kind of unit for temperature differences.Of course, just using a different function for converting differences is too complicated for him (Bernie wrote it 18 months ago, it's in the same utility class he used for the conversion of absolute values). Or adding another field to the type holding the value together with the unit, so that it can indicate if it's an absolute value or a difference, and have the conversion function taking that into account, ...
Well, now we have DeltaCelsius and DeltaKelvin. Let's ask the International Bureau of Weights and Measures to integrate these long missed units, and nominate Johnny for a Noble Prize.
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@BernieTheBernie ...are you making fun of the perfectly sane decision to make temperature difference a different type from absolute temperature value?
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@Gąska Well,
DeltaCelsius
andDeltaKelvin
would be the same by definition, so there's really no need for any conversion, ever.
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@Gurth said in Temperature Conversion:
@Rhywden said in Temperature Conversion:
Because that's actually quite useful. You have a 500 watt device which runs for two hours? Voilà, you just consumed 1 kWh of electrical energy and will have to pay 0.25€ for it.
Do any consumers make this kind of calculation on a regular basis?
It's the same reason why we're using liters and not m³ for denotating volumes of liquids. It's simply grounded in everyday units.
I don’t think that’s a valid comparison. The litre is technically unnecessary, true, but it has a name of its own like, say, the newton or the volt, not a compound name like kilowatt-hour. Convenience names tend to be there to simplify things — imagine if we expressed volumes of milk in m·m·m — yet kWh does pretty much the opposite.
electronVolts.
Your move.
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@Gąska said in Temperature Conversion:
And stop needlessly capitalizing random words like some kind of german, please.
You mean like "German"?
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@LaoC Mean like German? Man, that insult was totally uncalled for.
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@Carnage said in Temperature Conversion:
@PleegWat decagram is pretty common in parts of Europe.
Even common enough in Austria that you can drop the "gramm" and just order "fünf deka" of whatever.
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@PleegWat said in Temperature Conversion:
@Benjamin-Hall It's like those people who say "If you weigh 60 kilograms on Earth you'd weigh only 10 kilograms on the moon". It makes no sense because kilograms are a unit of mass, not force.
Heavy mass or inert mass?
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@mott555 said in Temperature Conversion:
Personally, I prefer all my units to be derived from cubic parsecs, and to hell with everyone else.
It's not that much weirder than the imperial system(s). ISTR an attoparsec per microfortnight is about an inch per second.
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@LaoC And a barn-megaparsec is about 3 milliliters.
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@PleegWat said in Temperature Conversion:
barn-megaparsec
This sounds like a huge unit for livestock capacity.
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@mott555 A barn is the area of a uranium nucleus. Blame nuclear scientists. Also see
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@PleegWat From the comments on that post:
It turns out that the barn-parsec and barn-megaparsec are useful concepts in astronomy.
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@PleegWat said in Temperature Conversion:
area of a uranium nucleus
like, the cross-section?
[a parsec is when] there is detected one arcsecond of apparent parallax between the star and other distant stars as Earth rotates around the Sun.
Earth's orbit is ~2 AU wide; the motion would be two arcseconds
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@kazitor said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
area of a uranium nucleus
like, the cross-section?
That was my assumption. If it was volume, multiplying that by a distance would give you an even more meaningless unit since it would have four dimensions.
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@mott555 said in Temperature Conversion:
Mass: Derived by the amount of Einsteinium contained in a cubic parsec.
I'm kind of surprised nobody commented on this one...an object like this would have a lot of very fun properties.
Also, I probably should have written it as "Defined as the amount of mass in a solid cube of Einsteinium where each edge is a parsec long."
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@mott555 They explicitly state it's an area. Just trying to figure out how that applies to an atomic nucleus.
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@mott555 said in Temperature Conversion:
@mott555 said in Temperature Conversion:
Mass: Derived by the amount of Einsteinium contained in a cubic parsec.
I'm kind of surprised nobody commented on this one...an object like this would have a lot of very fun properties.
Also, I probably should have written it as "Defined as the amount of mass in a solid cube of Einsteinium where each edge is a parsec long."
When I read it originally, I thought you meant a total mass of all Einsteinium atoms contained within a cubic parsec of the universe we live in on average. Which... isn't interesting at all.
But yeah, a cubic parsec of pure Einsteinium would indeed be very fun.
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@Gąska said in Temperature Conversion:
@LaoC Mean like German? Man, that insult was totally uncalled for.
The average German is not mean.
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@PleegWat said in Temperature Conversion:
@mott555 A barn is the area of a uranium nucleus. Blame nuclear scientists. Also see
Yes. There's also
shed
andouthouse
.
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@kazitor said in Temperature Conversion:
@mott555 They explicitly state it's an area. Just trying to figure out how that applies to an atomic nucleus.
Specifically, it's the energy-adjusted, effective cross-sectional area of a uranium nucleus for collisions with thermal neutrons. In essence, a cross-section (dimensions of L^2) is a measure of the probability of reaction for a particular reaction pathway. To actually get a probability, you have to scale it with a bunch of constants.
So something that has a cross-section of 1 barn has the same reaction probability for a given pathway that a single uranium atom has for fission under bombardment by thermal neutrons.
Note that the collision energy can change the cross-section by multiple orders of magnitude--in my graduate field, cross-section curves (as a function of collision energy) were always log-log plots. We covered between about 100 eV/amu up to ~20 keV/amu, over which the cross section would vary by 6-8 orders of magnitude.
Note that eV/amu is really a measure of speed-squared (dimensions of (L/T)^2), not energy, but it's the meaningful parameter.
Units are hard. But units are your friends.
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@dcon said in Temperature Conversion:
@Rhywden said in Temperature Conversion:
electronVolts
Volts are now computed in Javascript?
Explains the spike in electricity bill.
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@PleegWat said in Temperature Conversion:
And a barn-megaparsec is about 3 milliliters.
For stylistic reasons I prefer to shift over the mega to the barn. Megabarn-parsec sounds much cooler.
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@kazitor said in Temperature Conversion:
Quick question: in the US system of customary units, is
powerenergy usage measured in foot-pounds/minute hours or horsepower-hours or what?It isn't. Electrical energy consumption is measured in hybrid metric units — kilowatt-hours — just like (I guess) elsewhere. Natural gas energy consumption is measured in therms; a therm is a convenience unit defined as the energy contained in 100 cubic feet (or something like that; to verify) of natural gas at a specified temperature and pressure.
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@Gąska said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@Gąska said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@Benjamin-Hall It's like those people who say "If you weigh 60 kilograms on Earth you'd weigh only 10 kilograms on the moon". It makes no sense because kilograms are a unit of mass, not force.
Kilogram-force is a non-standard unit and is classified in SI Metric System as a unit that is unacceptable for use with SI.[4]
Should people stop using atmospheres, calories and carats as well? Because the cited source for that statement lists them as unacceptable as well.
They shouldn't stop using them, but they shouldn't use them for SCIENCE!
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@Gąska said in Temperature Conversion:
But yeah, a cubic parsec of pure Einsteinium would indeed be very fun.
In the DF sense?
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@HardwareGeek said in Temperature Conversion:
@Gąska said in Temperature Conversion:
But yeah, a cubic parsec of pure Einsteinium would indeed be very fun.
In the DF sense?
In the Dark Souls sense.
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@HardwareGeek said in Temperature Conversion:
In the DF sense?
In the “just how big is that black hole about to become anyway?” sense, with a side order of “and what sort of exotic radiation am I going to suffer from in the immediate future?”.
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@HardwareGeek said in Temperature Conversion:
@Gąska said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@Gąska said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@Benjamin-Hall It's like those people who say "If you weigh 60 kilograms on Earth you'd weigh only 10 kilograms on the moon". It makes no sense because kilograms are a unit of mass, not force.
Kilogram-force is a non-standard unit and is classified in SI Metric System as a unit that is unacceptable for use with SI.[4]
Should people stop using atmospheres, calories and carats as well? Because the cited source for that statement lists them as unacceptable as well.
They shouldn't stop using them, but they shouldn't use them for SCIENCE!
Is anyone using kgF for SCIENCE! though?
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@dkf said in Temperature Conversion:
@HardwareGeek said in Temperature Conversion:
In the DF sense?
In the “just how big is that black hole about to become anyway?” sense, with a side order of “and what sort of exotic radiation am I going to suffer from in the immediate future?”.
Hm, I'm still not convinced this is exotic enough to submit to http://what-if.xkcd.com
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@Rhywden said in Temperature Conversion:
electronVolts.
Your move.
So the existence of one awkward unit is an excuse to have more of them?
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@PleegWat said in Temperature Conversion:
@dkf said in Temperature Conversion:
@HardwareGeek said in Temperature Conversion:
In the DF sense?
In the “just how big is that black hole about to become anyway?” sense, with a side order of “and what sort of exotic radiation am I going to suffer from in the immediate future?”.
Hm, I'm still not convinced this is exotic enough to submit to http://what-if.xkcd.com
It hasn't been updated in a looooong time. I don't know if the lack is interesting submissions or author's time.
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@Gurth said in Temperature Conversion:
@Rhywden said in Temperature Conversion:
electronVolts.
Your move.
So the existence of one awkward unit is an excuse to have more of them?
You know what's awkward? Calculating electron energies in joules.
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@Khudzlin said in Temperature Conversion:
@PleegWat said in Temperature Conversion:
@dkf said in Temperature Conversion:
@HardwareGeek said in Temperature Conversion:
In the DF sense?
In the “just how big is that black hole about to become anyway?” sense, with a side order of “and what sort of exotic radiation am I going to suffer from in the immediate future?”.
Hm, I'm still not convinced this is exotic enough to submit to http://what-if.xkcd.com
It hasn't been updated in a looooong time. I don't know if the lack is interesting submissions or author's time.
Author's time. None of my submissions were posted yet, and it's been a long time.
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@Gąska I once questioned what would happen if every discussed scenario were to happen simultaneously.
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@kazitor well, the 0.9c baseball from episode 1 would prevent most of the rest from happening.
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@Gąska I think most of them prevent the rest.
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What If needs a time-waste warning, much like TV Tropes.
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@Gąska said in Temperature Conversion:
None of my submissions were posted yet, and it's been a long time.
Maybe he got stuck in the meta-discussions before he could actually finish reading them.
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@topspin there's a lot of metajokes on xkcd. If I had some free time, I could look through them all and determine which one is the most appropriate here.