Weird unit conversions

[enderlord99]

Discuss them here, please.

For example, how many knots per k'atun equal one G?

At 1/1296000 of a hertz, seconds of time and seconds of arc are equivalent.

[Khedrac]

Discuss them here, please.

For example, how many knots per k'atun equal one G?
Half a yes, but it's a very very silly measure.
Only half a yes because a knot can just be a nautical mile as well as a nautical mile per second.


At 1/1296000 of a hertz, seconds of time and seconds of arc are equivalent.
Quite simply no.

A hertz is one cycle per second (of time) as it does not have any equivalence with seconds of time or seconds of arc (which are completely different things anyway). I am guessing you mean that one second (arc) per second (time) is 1/1296000 hertz which isn't an equivalence, it is more of a direct result of the definition.

What I would consider a weird equivalence is that the "datum mile" is 6000 feet so can be considered a kilo-fathom (if you are willing to mix SI prefixes with imperial units).

[DavidSh]

Folklore points out that the barn-yard-atmosphere is a very small unit of energy, but I don't know how it converts to, say, electron-Volts.

[Brother Oni]

There's plenty of imperial units with metric prefixes - the one I use most often is the µin (micro inch) as a measure of average surface roughness of a material.

Concentrations can be a bit weird if both the solute and solvent are in the same units - for example a sugar solution of 0.5 g/ml of water looks weird when expressed as 0.5 g/g.

The ultimate expression of this are enzyme rate equations which process concentration units of substrate per concentration units of enzyme per time unit, so 0.5 g/g/g/g/second (g substrate / g solute / g enzyme / g solute / second).

[Knaight]

What I always found weird is just how close the cfs-hr and acre-in are as volume units, to the point where for napkin math you can treat them as interchangeable.

[Manga Shoggoth]

Only half a yes because a knot can just be a nautical mile as well as a nautical mile per second.

Nope. A knot is defined as one Nautical Mile per Hour. I would like to see your source for a Knot also meaning a Nautical Mile, as I have never seen that definition.

[gomipile]

Folklore points out that the barn-yard-atmosphere is a very small unit of energy, but I don't know how it converts to, say, electron-Volts.

One eV is about 17,292.4911 barn-yard-atmospheres.

[enderlord99]

What I always found weird is just how close the cfs-hr and acre-in are as volume units, to the point where for napkin math you can treat them as interchangeable.
Wow, only 30 cubic feet. That IS a small difference.

[Knaight]

Why would that be weird? The former is, by definition, 3600 cubic feet, right? And the latter is... (some large number over twelve) cubic feet.

How big is an acre again?

An acre is 43,560 square feet (66 by 660 being the measures used to generate that term, though the shape isn't actually in the definition). So an acre-in is 43,560 by 1/12, which works out to 3630 cubic feet. It's totally coincidental that they fit that closely, and incredibly convenient given how often you use both in hydrology if, for some reason, you can't just use the metric system.

EDIT: That's actually slightly closer than the Atmosphere-Bar conversion. 1 Atm is 1.013 bar, 1 Acre-in is 1.008 cfs-hr. Or, in percentage terms 1.3% larger as opposed to 0.8% larger. For unrelated units they're both really close, but breaking the Bar-Atm gold standard is really impressive.

[ezekielraiden]

Because of the ideal gas law: pressure-volume is a unit of energy. That one always weirded out my students whenever I explained it to them.

[Excession]

Pi seconds is a nanocentury.

[enderlord99]

Pi seconds is a nanocentury.

That's barely a significant figure more accurate than claiming 3 seconds is a nanocentury.

[Excession]

That's barely a significant figure more accurate than claiming 3 seconds is a nanocentury.

So? 3.15576 is still closer to pi them 3, and I find it to be a fun coincidence which seemed to be in the spirit of this thread.

[enderlord99]

So? 3.15576 is still closer to pi them 3, and I find it to be a fun coincidence which seemed to be in the spirit of this thread.

Yeah, that's fair.

[Khedrac]

Nope. A knot is defined as one Nautical Mile per Hour. I would like to see your source for a Knot also meaning a Nautical Mile, as I have never seen that definition.

Eep! - how did I make that mistake on the speed - thank-you for that correction.
Thinking about it I must have been confused (to make that first mistake) which is probably why I made the second - I think it less a definition and "a way I have seen the term used many years ago" which was probably incorrect right from the beginning.

[Eldan]

This thread is wonderful. Also, Imperial units are horrible.

[Vinyadan]

I have to say, I'd love to stand on a ship going a knot/second. Possibly strapped to the mast, while sirens around scream for their lives from the incoming tsunami.

[Eldan]

That's not that fast, is it? A mile a second, about 300 km/h? I mean, it is for a boat, but cars* have gone three or four times that.

*If your definition of "car" includes "jet engines with wheels"

[Domino Quartz]

That's not that fast, is it? A mile a second, about 300 km/h? I mean, it is for a boat, but cars* have gone three or four times that.

*If your definition of "car" includes "jet engines with wheels"

Eh? A nautical mile a second is roughly equivalent to 6667 km/h.

[Eldan]

Yeah... how did I get there...

[Khedrac]

Yeah... how did I get there...

I'm glad I'm not the only one having brain failures.

As for 300 km/h in a boat, that is doable but hard, the world record is 318 mph (511km/h) and was set in 1978. The problem is boats travelling at speed tend to flip killing the pilot the moment anything goes wrong.

[Knaight]

That's not that fast, is it? A mile a second, about 300 km/h? I mean, it is for a boat, but cars* have gone three or four times that.

*If your definition of "car" includes "jet engines with wheels"
A mile a second would be 3600 miles per hour, or 6677 km/hr. That's about Mach 5.4, so it's been broken by spacecraft and the like. On the other hand...


I have to say, I'd love to stand on a ship going a knot/second. Possibly strapped to the mast, while sirens around scream for their lives from the incoming tsunami.
A knot is already a velocity term, for a nautical mile per hour. That makes a knot/second an acceleration. A nautical mile is 1,852 meters, which makes a knot 1,852 meters/hr or 0.514 meters per second. Thus the acceleration term is only 0.514 meters per second squared, or about 0.0525 G.

Odds are pretty good you've been on a ship going through that acceleration if you've been on a ship at all, and even then it was probably as part of a ramp up phase where it's undergoing positive jerk that ends up with a higher acceleration, or a subsequent ramp down phase with negative jerk as the water resistance picks up.

[DavidSh]

A knot is already a velocity term, for a nautical mile per second.

You will want to edit that to "a nautical mile per hour", I think.

[Grey_Wolf_c]

a knot [is] a nautical mile per second.


Nope. A knot is defined as one Nautical Mile per Hour.


A knot is already a velocity term, for a nautical mile per second

You guys really need to compare notes.

GW

[Knaight]

You guys really need to compare notes.

GW

Fixed. The funny part is that I did all the math using the correct definition, and somehow just threw in a typo-of-sorts before launching into it.

[Manga Shoggoth]

Eep! - how did I make that mistake on the speed - thank-you for that correction.
Thinking about it I must have been confused (to make that first mistake) which is probably why I made the second - I think it less a definition and "a way I have seen the term used many years ago" which was probably incorrect right from the beginning.

You are probably remembering that speed at sea used to be measured using a knotted rope and a drag, counting the number of knots that passed through in a given time (30 seconds, if I recall correctly).

[hamishspence]

Did anyone else think of tabletop game model conversions when they saw the title of the thread?

[farothel]

There are several Wikipedia pages on this: https://en.wikipedia.org/wiki/List_of_unusual_units_of_measurement
https://en.wikipedia.org/wiki/List_of_humorous_units_of_measurement

I especially like the ones where you have a big unit combined with something small to get something useful for daily use.
For instance the atto-parsec. Using the same logic, the pico-parsec is about 30km. So using this I can say I do the Kessel run in about 0.5 pico-parsec. Kessel is a village in Belgium about that distance from my house.

[Knaight]

I especially like the ones where you have a big unit combined with something small to get something useful for daily use.

The really tiny units plus large prefixes can be similarly fun. For instance, a tera-angstrom is ten centimeters.

On a slightly different note, am I the only one somewhat disappointed by the existence of the metric tonne? I get why it's useful, but it's exactly equivalent to the megagram, which is just a more fun term.

[Khedrac]

On a slightly different note, am I the only one somewhat disappointed by the existence of the metric tonne? I get why it's useful, but it's exactly equivalent to the megagram, which is just a more fun term.
I would not go there, but none of the SI units of mass follow the SI naming rules with the possible exception of the kilogram.

The prefix should be applied to the defined unit, and the defined unit is the kilogram - therefore, according to SI standards, a thousandth part of a kilogram should be a milikilogram and not a gram.

As for the metric tonne, I suspect it got created because they wanted to be able to refer to things by the "ton" (homophone) and needed a metric replacement for the ton (imperial) thus a handy value got the name slapped on it.

[Knaight]

I would not go there, but none of the SI units of mass follow the SI naming rules with the possible exception of the kilogram.

The prefix should be applied to the defined unit, and the defined unit is the kilogram - therefore, according to SI standards, a thousandth part of a kilogram should be a milikilogram and not a gram.
On the other hand the term milikilogram nicely demonstrates why this is a bad idea. Though just calling a kg a gram, a gram a milligram, etc. when the system was devised would have worked just fine, and avoided the one piece of weirdness that is the kg being the base unit.


As for the metric tonne, I suspect it got created because they wanted to be able to refer to things by the "ton" (homophone) and needed a metric replacement for the ton (imperial) thus a handy value got the name slapped on it.
I suspect it's a mix of that and potential issues with both mg and Mg showing up as distinct units.

[jayem]

Mostly use metric, so rarely have truly weird unit conversions. Occasionally have weird values (though it's not too hard to avoid them, so if European designed it's the Imperial version that gets the double does of screwiness, whereas the other way it's split evenly). Tensile strengths work really nicely.

We do have a machine that measures cc/sec/(mm H2O)*(circ inch) which we have to convert to mm/s (which fortunately just requires multiplying by 2).

(H2O) It's actually just stated at the given pressure as it isn't truly linear.
(circ inch=5.07cm^2=0.78 sq inch, it's a circle with a 1" diameter) I think in it's original use the same applied, or it was used in some equation where the radius matters.

Oh but trouser Sizes, trying to work out what system they use and what kind of person...

[Telok]

[QUOTE=jayem;23282543Oh but trouser Sizes, trying to work out what system they use and what kind of person...[/QUOTE]

I've heard a couple of quite heartfelt rants about bra sizes, different manufacturers, and the complete lack of standards.

[Rockphed]

I've heard a couple of quite heartfelt rants about bra sizes, different manufacturers, and the complete lack of standards.

Yes, well if women had the decency to at least standardize their own equipment, it wouldn't be so hard to fit supportive garments. It's just unprofessional having parts of a nominally symmetric body be that different in size. *ducks flung vegetables*

In all seriousness, women's clothing is, in general frustrating for anyone not built like a rail to get to fit properly. My wife frequently laments just about every article of clothing she owns. Either they don't fit right in one spot or they don't fit right in another. Often they are made of some stupid fabric that is uncomfortable. Then there are the geniuses who put seams in bad places. Half the time she steals my clothes to get stuff that fits right.

[Khedrac]

On the other hand the term milikilogram nicely demonstrates why this is a bad idea. Though just calling a kg a gram, a gram a milligram, etc. when the system was devised would have worked just fine, and avoided the one piece of weirdness that is the kg being the base unit.
What they should have done was just update the defined unit so that a gram was defined as one thousandth part of the definition of the kilogram - probem solved. Especially as they have redefined the kilogram definition several times (starting with Carbon 12 and ending with the standard kilogram kept in Paris).


I suspect it's a mix of that and potential issues with both mg and Mg showing up as distinct units.
Probably - though that hasn't stopped other areas. E.g. decimetres and decametres (dm and Dm).

The last gave me a lot of trouble when I was trying to find out what "DM" in a file format definition meant - no amount of internet searching found the answer (which I knew to be close to a mile), it wasn't until I found someone who knew that it was a "data mile" that I could look it up and get the details - another reason for calling it a kilofathom (kfm?).

[Lord Torath]

Yes, well if women had the decency to at least standardize their own equipment, it wouldn't be so hard to fit supportive garments. It's just unprofessional having parts of a nominally symmetric body be that different in size. *ducks flung vegetables*

In all seriousness, women's clothing is, in general frustrating for anyone not built like a rail to get to fit properly. My wife frequently laments just about every article of clothing she owns. Either they don't fit right in one spot or they don't fit right in another. Often they are made of some stupid fabric that is uncomfortable. Then there are the geniuses who put seams in bad places. Half the time she steals my clothes to get stuff that fits right.Also, lack of pockets, or the presence of fake pockets. Yes, seriously, they make women's pants with fake pockets, and pockets that are about 1 inch deep. What can you put in an inch-deep pocket? A paperclip? A folded dollar bill? Certainly not a phone or your keys.

One of my favorite units is Poops per Bird per Hour (https://what-if.xkcd.com/11/). That whole article is full of fun unit conversions. :smallbiggrin:

[Peelee]

This thread is wonderful. Also, Imperial units are horrible.
Am oldie but a goodie (well, only six years, but still):

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 **** yourself,’ because you can’t directly relate any of those quantities.

[Eldan]

Also, lack of pockets, or the presence of fake pockets. Yes, seriously, they make women's pants with fake pockets, and pockets that are about 1 inch deep. What can you put in an inch-deep pocket? A paperclip? A folded dollar bill? Certainly not a phone or your keys.

One of my favorite units is Poops per Bird per Hour (https://what-if.xkcd.com/11/). That whole article is full of fun unit conversions. :smallbiggrin:

Oh, ecologists are marvellous with our axes and units. We are after all the invention of the EPC, or Extra-pair Copulation as a standard term. "Infections per restaurant visit", "Itches/hour/rat"... the list is endless.

Edit: mostly unrelated, but I just opened this article:


On a related note, the annual (intentionally lighthearted) Christmas issue of the British Medical Journal was released this week, and it included an analysis by researchers in Sweden of Bob Dylan lyrics found in the biomedical literature. The study was inspired by the authors’ colleagues, who revealed in 2014 that they had been sneaking Dylan lyrics into their articles for years as part of a long-running bet. The list includes such title gems as “Like a Rolling Histone” and “Knockin’ on Pollen’s Door: Live Cell Imaging of Early Polarization Events in Germinating Arabidopsis Pollen.” Although the authors found few Dylan references prior to 1990, since then, the references have increased exponentially, with the two most cited songs being “The Times They Are a-Changin’ ” (135 articles) and “Blowin’ in the Wind” (36 articles). Interestingly, the journal Nature had a particularly high number of articles (six total) that cited Dylan.

[5a Violista]

Am oldie but a goodie (well, only six years, but still):

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 **** yourself,’ because you can’t directly relate any of those quantities.

(The funny part is that the SI unit of energy is actually the Joule, not the calorie, so you still have to do unit conversions anyway since you'll likely need/have the energy in terms of Joules instead of calories in most cases)

The US actually does have an equivalent unit, the Btu (British thermal unit); it's weird how it's named after Britain but used exclusively in the US (with the exception of natural gas sales: Great Britain commonly uses a unit derived from the Btu called the Therm. Weird. Also, apparently, they passed legislation to change that to Joules but the wholesale market didn't want to change; meanwhile, the US frequently use cubic feet to trade natural gas. Coincidentally, 1 therm is slightly more than 100 cubic feet, so I guess that also counts as a weird unit conversion for the purposes of this thread.)

Anyway, to know how many Btu it takes to boil a room-temperature gallon of water, all you have to do is know how much a gallon of water weighs and how you define room temperature, which is 8.34 lbs if you're in the US, and about 72 °F, so volume * density * temperature difference = 8.34 * 140 = <the answer is left as an exercise to the reader>

[gomipile]

I'm surprised no one has mentioned any of the classic joke unit conversions involving furlongs. They've led to the creation of a joke unit system: the furlong/firkin/fortnight system.

Two examples from Wikipedia:

In the VMS operating system, the TIMEPROMPTWAIT variable, which holds the time the system will wait for an operator to set the correct date and time at boot if it realizes that the current value is bogus, is set in microfortnights.

The speed of light is 1.8026×1012 furlongs per fortnight or 1.8026 megafurlongs per microfortnight.

The speed of light in furlongs per fortnight was on a poster on the door to the computer science lab at my high school in the 90s. That was my first introduction to jokes involving obscure unit conversions. Unfortunately I didn't learn about the firkin until very recently, or I would have referenced it a lot during the 2000s, I'm sure.

[Brother Oni]

I suspect it's a mix of that and potential issues with both mg and Mg showing up as distinct units.

It's why there's a move away from Calorie to kilocalorie to make the distinction more clear from calorie, although inertia and ease of use keeps Calorie in circulation.

Another common one is that Americans pharmaceuticals use mc instead of µ for the 'micro' SI prefix, the main reason being that a hand written µ can look very similar to a m.

Despite it being listed as good clinical practice, there's still accidental patient overdose deaths every year.

[Knaight]

It's why there's a move away from Calorie to kilocalorie to make the distinction more clear from calorie, although inertia and ease of use keeps Calorie in circulation.
That the Calorie and calorie are different units is one of the single stupidest nomenclature systems I've ever come across, and this includes multiple different volume units based on the barrel, one of which is the barrel of oil (so a barrel of oil, in the sense of a barrel of volume that happens to contain oil, is actually a different volume than a barrel of oil, the separate volume unit). The kcal fixes this, and should have been in there from the beginning.

Dropping them entirely in favor of the joule also works for me.


Another common one is that Americans pharmaceuticals use mc instead of µ for the 'micro' SI prefix, the main reason being that a hand written µ can look very similar to a m.

Despite it being listed as good clinical practice, there's still accidental patient overdose deaths every year.
So what do they use for the 'mili' prefix? Also this just seems like a terrible idea.

[Grey_Wolf_c]

So what do they use for the 'mili' prefix? Also this just seems like a terrible idea.

I'm guessing they use "m", thus the potential for overdose when someone's µ is misread as an m. Not sure why you feel that reducing ambiguity is a terrible idea. I mostly agree that "mcl" is likely more distinct from "ml" than "µl" in most people's handwriting.

Grey Wolf

[halfeye]

That the Calorie and calorie are different units is one of the single stupidest nomenclature systems I've ever come across,

That would presumably be down to the marketing departments of the food companies.


The kcal fixes this, and should have been in there from the beginning.

Dropping them entirely in favor of the joule also works for me.

Yeah, but now there are kilojoules all over food packages, which is okay I guess, it will hopefully work out to something that's actually physically sensible in the end.

[Knaight]

I'm guessing they use "m", thus the potential for overdose when someone's µ is misread as an m. Not sure why you feel that reducing ambiguity is a terrible idea. I mostly agree that "mcl" is likely more distinct from "ml" than "µl" in most people's handwriting.

Grey Wolf

I didn't catch the c when reading, and read that as just using ml for microliter. Using mcl seems fine.

[Khedrac]

The US actually does have an equivalent unit, the Btu (British thermal unit); it's weird how it's named after Britain but used exclusively in the US (with the exception of natural gas sales: Great Britain commonly uses a unit derived from the Btu called the Therm. Weird. Also, apparently, they passed legislation to change that to Joules but the wholesale market didn't want to change; meanwhile, the US frequently use cubic feet to trade natural gas. Coincidentally, 1 therm is slightly more than 100 cubic feet, so I guess that also counts as a weird unit conversion for the purposes of this thread.)
Just to confuse, the energy value of gas (natural or otherwise) depends on the mxiture, so any volume to energy conversion has to use the calorific value of the gas (which I remember as going up with increased humidity to my surprise).

This then makes life interesting as all gas meters read volume, but the billing in the UK market is mainly done on energy (I don't recall coming across any wholesale contracts in volume, but it was 20 years ago I worked in the sector); thus all of the gas billing is done by very rough averages, especially in the domestic market. (With the gas in the pipes being a blend from multiple sources, I don't see how measuring the calorific value in specific locations really gives an accurate read of the calaorific value of the gas delieered over 6 months - the usual interval between domestic readings - it's an average of an average of an average.)

Edit: yes 20 year ago the Btu was used occasionally, along with the therm, but what we normally used was the kilojoule. I am not going to complain if we have now entirely bequeathed use of the Btu to the colonies.

[veti]

My car averages 14.5 kilofurlongs per hogshead (in the city), and that's the way I like to brag about it. Nobody's beaten it yet...

[Rockphed]

My car averages 14.5 kilofurlongs per hogshead (in the city), and that's the way I like to brag about it. Nobody's beaten it yet...

Distance per volume is the wrong unit, it should be volume per distance to allow better comparisons of efficiency. Going to 30 miles per gallon from 15 miles per saves exactly as much fuel as going from 20 miles per gallon to 60 miles per gallon (in both cases saving 3 1/3 gallons per 100 miles), but because of the way our brains work, a gain of 40 seems so much better than a measly gain of 15.

As to your claimed fuel efficiency: that is a little better than my driving of my mid-sized sedan (you save about 0.6 gallons per 100 miles). And you missed a chance to cite it in kilo-furlongs per firkin (2.487).

[Vinyadan]

Isn't anyone going to say anything about the denier/denaro? Wikipedia doesn't have an English page for it, but it's a linear density measuring unit, mostly used by girls to choose how warm their socks and tights should be.

1 den =
SI 1/9 × 10−6 kg/m
CGS 1/9 × 10−5 g/cm
MTS 1/9 × 10−3 t/m
US ≈0,75 × 10−7 lb/ft

[Lord Torath]

A calorie also has a different value based on the temperature of water. It varies between 4.182 and 4.204 J/ml (https://en.wikipedia.org/wiki/Calorie#Definitions).

[halfeye]

A calorie also has a different value based on the temperature of water. It varies between 4.182 and 4.204 J/ml (https://en.wikipedia.org/wiki/Calorie#Definitions).

They didn't define the calorie at STP? :smallconfused: :smallsigh: :smalleek: :smallbiggrin:

[Knaight]

They didn't define the calorie at STP? :smallconfused: :smallsigh: :smalleek: :smallbiggrin:

They did for the thermochemical calorie, according to that page. The rest are more specialized terms unlikely to be used except explicitly. It's sort of like how the "mole" on its own is the same as the "gram mole", but there's technically a mole for every mass unit.

[keybounce]

I like Gallons per fortnight, myself.


This thread is wonderful. Also, Imperial units are horrible.

A very good argument can be made that in episode 4 they were incredibly good except when they were deliberately aiming to miss / under orders to let them escape. You know, to track the rebel base.

[Mando Knight]

A calorie also has a different value based on the temperature of water. It varies between 4.182 and 4.204 J/ml (https://en.wikipedia.org/wiki/Calorie#Definitions).

The calorie is defined per gram, not per milliliter--while more-or-less incompressible, water's density also changes by temperature.

[Knaight]

The calorie is defined per gram, not per milliliter--while more-or-less incompressible, water's density also changes by temperature.

It's also defined at a particular temperature-pressure (or more accurately, it was before the definition was standardizes in terms of joules). Technically this means that liquid water doesn't take exactly one calorie to raise one degree, though it's a very, very small deviation if you're not supercooling, superheating, or using fairly dramatic pressure conditions.

[factotum]

According to my calculations, the motorway speed limit in the UK is approximately one parsec per petasecond. That's about as weird as I want my units to be, frankly... :smallsmile:

[Eldan]

Nice.

One parsec/petasecond comes out to 30.9 m/second or 111 km/h or 69 mph. So, that's now a good answer to give if a policeman asks you if you know how fast you were going :smalltongue:

[Cespenar]

With apologies, the relevant xkcd link (https://xkcd.com/1047/). :smalltongue:

[AvatarVecna]

With apologies, the relevant xkcd link (https://xkcd.com/1047/). :smalltongue:

Speaking of XKCD, I recall that one of the What Ifs brought up an interesting measurement - namely, the oddity of unit simplification involved when discussing "miles per gallon". A gallon is a three-dimensional measurement of volume, while a mile is a one-dimensional measurement of distance...which means you can theoretically imagine your gas usage as leaving a very small diameter, very long cylinder trailing behind your car as you drive, and your gas milage can be converted into the surface area the end of that cylinder has.

EDIt: Found it. (https://what-if.xkcd.com/11/)

[Jormengand]

One of my homebrew classes, the Adventurer, references the cplv-1/2 (copper piece per root level) as a unit.

[Xyril]

(The funny part is that the SI unit of energy is actually the Joule, not the calorie, so you still have to do unit conversions anyway since you'll likely need/have the energy in terms of Joules instead of calories in most cases)


Except you don't, because the Joule is defined as the amount of work done by applying a force of one Newton over one meter--the Newton is, in turn, the amount of energy required to accelerate one kilogram at 1 m/s^2. So on an abstract level, we're once again talking about trivial unit conversions. I suppose you could argue that on a practical level, actually clocking the acceleration on a kilogram of water to see how much for it takes to accelerate it would be a bit messy.

[Knaight]

Except you don't, because the Joule is defined as the amount of work done by applying a force of one Newton over one meter--the Newton is, in turn, the amount of energy required to accelerate one kilogram at 1 m/s^2. So on an abstract level, we're once again talking about trivial unit conversions. I suppose you could argue that on a practical level, actually clocking the acceleration on a kilogram of water to see how much for it takes to accelerate it would be a bit messy.

We're talking about heating water, not moving it - which doesn't mean you need unit conversions, but does mean you need to know the specific heat of water as well as the relevant heat equation to handle the specific heat of water you've chosen (q=mcΔT for a constant, dq/dT=mc as a starting point for all others where c is generally a function of T).

[jayem]

We're talking about heating water, not moving it - which doesn't mean you need unit conversions, but does mean you need to know the specific heat of water as well as the relevant heat equation to handle the specific heat of water you've chosen (q=mcΔT for a constant, dq/dT=mc as a starting point for all others where c is generally a function of T).

I suppose from a Energy-Meter-Second view you could argue that Heat Capacity is a unit conversion (for exactly what that average accel_distance is*, or something very easily derivable from the boltzman constant) multiplied by however many different accelerations you applied.
[Actually creating a proper argument would require far more rigour than would be fun for loophole abuse]

*well obviously in this the joule is the base unit, quite how you get back to describing kinetic energy I don't know (perhaps via the Lorentz transformation) but from there via statistical thermodynamics to get 'Temperature'. In any case as flanders&swann put it "heat is work and work is heat"

[Manga Shoggoth]

In any case as flanders&swann put it "heat is work and work is heat"

"Oh, I'm hot!"
"Hot? That's because you've been working!"

...Because there's not enough Flanders and Swann in the world. I won't link to it, but The Laws of Thermodynamics (monologue plus song) is well worth a search.

[5a Violista]

Except you don't, because the Joule is defined as the amount of work done by applying a force of one Newton over one meter--the Newton is, in turn, the amount of energy required to accelerate one kilogram at 1 m/s^2. So on an abstract level, we're once again talking about trivial unit conversions. I suppose you could argue that on a practical level, actually clocking the acceleration on a kilogram of water to see how much for it takes to accelerate it would be a bit messy.

The SI unit for heat is, in fact, the Joule, for reasons stated by other posters.

https://en.wikipedia.org/wiki/Heat#Notation_and_units