Bar Conversion: Volume & Temperature Units

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Discussion Overview

The discussion revolves around the conversion of the unit "bar" in relation to volume and temperature, exploring its definitions and implications in different contexts. Participants engage in clarifying the relationships between various units of pressure, including pascals and kilogram-force per square meter, while also touching on informal uses of these units.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants state that 1 bar is equivalent to 100,000 pascals, while others clarify that it can also be expressed in terms of kilogram-force per square meter.
  • There is a discussion about the conventional representation of units, with some participants expressing preferences for different notations.
  • One participant notes that in common usage, a bar is often referred to as "kg/cm^2," leading to a discussion about the historical context and conversion discrepancies.
  • Another participant challenges the idea that the acceleration due to gravity (g) was rounded to 10 N/kg, asserting that it remains approximately 9.80665 m/s².
  • There is a humorous exchange regarding the conversion of bar to an unconventional unit, "horsepower-decades per cubic furlong," highlighting the playful nature of the discussion.
  • Some participants emphasize that the definitions of units can vary between scientific and everyday contexts, particularly in Europe.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and conversions of the bar, with no consensus reached on the historical context or the accuracy of certain claims regarding the unit's relationship to other measurements.

Contextual Notes

The discussion includes references to informal and formal definitions of pressure units, highlighting potential confusion arising from different contexts in which these units are used.

BMcN
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What the conversion for bar so that I can use it to work out volume and temprature? Whats the units?
 
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Bit higher than I remember, but thanks!
 


Originally posted by Ambitwistor
1 bar = 100,000 pascals = 100,000 kg/m/s2
Should be kg/m-s2

- Warren
 
Not to be a pain in the ass, but I'd normally think

kg/m/s^2 = kg s^2 / m

But I guess it does come down to the conventional order of operations. I guess you win. Gack. I personally hate when people describe accelerations as "meters per second per second" i.e. m/s/s, for the same reason.

- Warren
 
Interesting note:

In the "common" world, a bar has the unit "kg/cm^2". THis is referring to the weight of one kilogram per square centimeter. THis of course translates to only 98,010 N per square meter, but somewhere along the line, "g" got upgraded to 10 N/kg instead of 9.801 N/kg.
 
So what is it in hpdpcf's (horsepower-decades per cubic furlong)?

Njorl
 
Originally posted by Chi Meson
Interesting note:

In the "common" world, a bar has the unit "kg/cm^2". THis is referring to the weight of one kilogram per square centimeter. THis of course translates to only 98,010 N per square meter, but somewhere along the line, "g" got upgraded to 10 N/kg instead of 9.801 N/kg.
Uh... no.

1 bar is defined to be 100 kilopascals. A pascal is one Newton per square meter. One kilogram-force is g Newtons. Therefore, one pascal is (1/g) kilogram-force per square meter. Therefore, one bar is 100,000/g kilograms-force per square meter.

g is accepted to be 9.80665 m/s^2, so one bar is 10,197.1621298 kilograms-force per square meter.

I have no idea where you got the idea that someone rounded g to 10 m/s^2, but it never happened.

- Warren
 
You think you're better than me, punk?








- Warren
 
  • #10
Originally posted by chroot
Uh... no.

1 bar is defined to be 100 kilopascals. A pascal is one Newton per square meter. One kilogram-force is g Newtons. Therefore, one pascal is (1/g) kilogram-force per square meter. Therefore, one bar is 100,000/g kilograms-force per square meter.

g is accepted to be 9.80665 m/s^2, so one bar is 10,197.1621298 kilograms-force per square meter.

I have no idea where you got the idea that someone rounded g to 10 m/s^2, but it never happened.

- Warren

That's not what I meant, really. In Europe, the unit of bar and kg/cm^2 is used interchangeably (not by scientists, but by people pumping their bike tires). I remember several times over the years hearing anecdotaly that the bar was based on the "kg/cm^2" but was then redefined to be essentially 10 N/cm^2 (actually 1,000,000 dynes per cm^2)to be scientifically correct.

So g was not the one that was adjusted. It's the bar that was raised.
 

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