Imperial versus metric

[RCgothic]

It's a capital letter if the unit is named after a person.

James Watt. Baron Kelvin. Anders Celcius. Rolf Sievert. James Joule. Andre-Marie Ampere. Joseph Henry. All capitalised units.

gram, second, metre, mole, candela, not so much.

[StrandedonEarth]

 

Edited August 4, 2022 by StrandedonEarth

[kerbiloid]

4 hours ago, RCgothic said:

It's a capital letter if the unit is named after a person.

It's obvious, and it's silly.

Do we name the variables and constants in different case letters?

The unit name/abbreviation is a postfix to the numeric, explaining what's that. They should be equal. The Newton is not Newton.

Should we additionally write the unit names in the Ancient-Egyptian cartouches to show which scientist was greater than others?

Edited August 4, 2022 by kerbiloid

[Gargamel]

41 minutes ago, kerbiloid said:

o we name the variables and constants in different case letters?

Yes.   i usually implies an imaginary number while I implies Current.       E is Energy, and e is Euler’s number.    And pi is 3.14 and Pie is good. 

[kerbiloid]

Just now, Gargamel said:

Yes.   i usually implies an imaginary number while I implies Current.       E is Energy, and e is Euler’s number.    And pi is 3.14 and Pie is good. 

This is just for usability. But not out of greater respect to energy than to Euler.

Even looks that vice versa, lol.

Edited August 4, 2022 by kerbiloid

[wumpus]

13 hours ago, Gargamel said:

Yes.   i usually implies an imaginary number while I implies Current.       E is Energy, and e is Euler’s number.    And pi is 3.14 and Pie is good. 

I still insist on using "j" for -1^.5, especially where current is nearby.

[mikegarrison]

17 hours ago, kerbiloid said:

Do we name the variables and constants in different case letters?

Yes.

Whether you are talking math or computer languages, generally A is not a, Σ is not σ, etc.

[RCgothic]

Symbols don't follow the same rules as units.

[kerbiloid]

6 hours ago, mikegarrison said:

Yes.

Whether you are talking math or computer languages, generally A is not a, Σ is not σ, etc.

Once again, do we call energy E and Euler's constant e because we respect the energy more than Euler with his constants?

[mikegarrison]

Just now, kerbiloid said:

Once again, do we call energy E and Euler's constant e because we respect the energy more than Euler with his constants?

Why are you asking me? I didn't make that claim.

[kerbiloid]

Any system of units which is not based on the golden section is not perfect.

[kerbiloid]

The duodecimal system could be easily compatible with the hexadecimal one.

Zero, Ace, 2, ..., 9, 10, Elf. Dozen, Jack, Knight, Queen, King

Also the playcards could become hexadecimal.

Edited September 4, 2022 by kerbiloid

[RKunze]

On 8/3/2022 at 9:01 PM, kerbiloid said:

Also, who was Gram?

Danish bacteriologist from the 19th century. Invented a method to stain biological samples for microscoping that is still in use today.

[Hannu2]

On 8/4/2022 at 9:57 PM, wumpus said:

I still insist on using "j" for -1^.5, especially where current is nearby.

Imaginary unit is usually written as j in electrical engineering. i(t) is instantaneous current (as a function of time) and I is usually RMS-value.

You write that sinusoidal 50 Hz AC current I =10 A which means i(t) = 10A * sqrt(2) * exp(2*pi*50 Hz*t*j), where j is imaginary unit and t is time. Calculations use complex currents which arguments is phase in relative to some reference. Actual physical current is real value of complex current.

[Beamer]

I for one had a good laugh when the Artemis mission manager (Michael Sarafin) mentioned that the temperature of the engines needed to be 500 Rankine for launch to be feasible

Interesting factoid: our 12/60 based scales come from the way the Babylonians used to count on their fingers. Touch the tip of your left thumb to the first bone of your index finger, that's 1. Second bone is 2, 3rd bone is 3. Then move your thumb tip to the first bone on your middle finger, that's 4. Continue going down fingers/bones until you hit 12 at the 3rd bone of your pinky. To indicate 13, raise 1 finger on your right hand and add 1 with the left hand. After going 5 rounds of 12 (=60) you run out of bones/fingers/hands and have to start over.

That's the historical basis for any of our 12/60 based unit systems.

 

[Beamer]

On 8/5/2022 at 6:20 AM, kerbiloid said:

Once again, do we call energy E and Euler's constant e because we respect the energy more than Euler with his constants?

We use 'e' for Euler's number because that's what Euler himself chose to use for it in his writings. It was discovered by Bernoulli, not by Euler, and originally represented as 'b'. Euler's constant is denoted by the (lowercase) greek letter gamma and is an entirely different beast (0.577...).

The rule that capitals are named after a person may have some truth in the units from physics, but I don't think that rule works in mathematics. For some reason, mathematicians generally seem to prefer lowercase letters.

 

[kerbiloid]

There is a common misconception that the Ivy Mike "Sausage" thermonuke was 82 t heavy.

Actually it was just 74 t.
82 t it was in "short tons"

Edited October 21, 2022 by kerbiloid

[TomKerbal]

Very funny discussion :-)

Btw, you could also check:

https://en.wikipedia.org/wiki/International_System_of_Units

https://en.wikipedia.org/wiki/SI_derived_unit

What's written there is exactly how I learned it at school/university.

Sometimes I really like Wikipedia.

Best wishes for usage of "Rankine" temperature unit !

Tom (using the "i" for the imaginary unit.. and "j" for current density)

[Pthigrivi]

I seriously, really need the US to do make the switch. Im an architect and this is hellish. I spend a lot of time in CAD. Why do have the decimal version of 13/16th of an inch occupying space in my brain. I have no means of backing this up but I bet we lose 2 points off GDP on this stupidity alone. It's fine. Take 10 years. Take 15. Just start making it happen. Start mandating both in transportation, material specifications, let it sink in. 5 years implementing dual systems, 5 years with both, and 5 years extracting out imperial. Its absolute madness. 

Edited January 5, 2023 by Pthigrivi

[StrandedonEarth]

8 minutes ago, Pthigrivi said:

I seriously, really need the US to do make the switch. Im an architect and this is hellish. I spend a lot of time in CAD. Why do have the decimal version of 13/16th of an inch occupying space in my brain. I have no means of backing this up but I bet we lose 2 points off GDP on this stupidity alone. It's fine. Take 10 years. Take 15. Just start making it happen. Start mandating both in transportation, material specifications, let it sink in. 5 years implementing dual systems, 5 years with both, and 5 years extracting out imperial. Its absolute madness. 

I totally agree. My concern is how this will fly in the world of Air Traffic Control...

[Pthigrivi]

1 hour ago, StrandedonEarth said:

I totally agree. My concern is how this will fly in the world of Air Traffic Control...

Jebus are they not already on metric? Do we really have military aircraft flying in the same airspace as commercial on different standards?

[StrandedonEarth]

Just now, Pthigrivi said:

Jebus are they not already on metric? Do we really have military aircraft flying in the same airspace as commercial on different standards?

I admit I don't know for sure, but I thought they were still tracking flight levels in hundreds of feet and speed in knots?

[18Watt]

35 minutes ago, StrandedonEarth said:

I thought they were still tracking flight levels in hundreds of feet and speed in knots?

Yes.  Speed in knots or Mach, altitude in feet.  Flight Levels are hundreds of feet.  US and Canada report altimeter settings in inches of mercury, although the setting is available in most of the rest of the world in hPa, kPa, or millibars.

Fuel is ordered in gallons, mass is in pounds in the US and Mexico.  Not sure about the rest of the world, but in Canada fuel is normally weighed in pounds, but ordered in liters.  So that can be odd.  

[Kerbart]

2 hours ago, StrandedonEarth said:

I totally agree. My concern is how this will fly in the world of Air Traffic Control...

The issue with the US sticking to imperial measurements is not that (as much as it does) imperial has shortcomings; it's that the rest of the world doesn't use it. That's where conversion errors come from. ATC doesn't have that problem; everyone; everyone, worldwide, uses nautical miles for distance and feet for altitude. As long as you're all using the same units, there's not an issue. Switching to metric wouldn't really have benefits, be a gigantic operation and arguably be unsafe.

International trade is a good example. Everyone agrees on the length of a standard container; it's 40 foot*. Nobody calls that a 12.19m container and no one is insane enough to demand that the standard size should be 12m; Everyone agrees on the same unit, 40', and little need to switch (Ironically, temperature for reefer containers is set in Celsius, not Fahrenheit. Once in a while you'll have an American shipper learn that lesson with a container full of rotten meat).

* Yes, there are 20' containers, and 45' containers and occasionally a few 53' containers will make their way across the Pacific, but by far the most prolific size is 40'

[Ryaja]

They should teach metric in schools first, unless it is in nautical terms I've heard imperial is better for that.