What are some of these scales based on?

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Discussion Overview

The discussion revolves around understanding various units of measurement, specifically the Réaumur temperature scale, and the pressure units torr and bar. Participants seek clarification on the definitions and bases of these units, touching on both theoretical and practical aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes that 1 calorie is defined as the energy required to raise the temperature of 1 kg of water by 1°C, while clarifying the distinction between calorie (small c) and Calorie (large C).
  • Another participant provides a definition of the bar as the pressure created by one million dynes of force on one square centimeter, equating it to 100,000 pascals and noting its proximity to atmospheric pressure.
  • A participant mentions the difficulty in finding information about the Réaumur scale due to language barriers, specifically encountering French sources.
  • Links to external resources are shared, including a Britannica article and Wikipedia references, to assist in understanding the units discussed.
  • One participant highlights that the unit of pressure commonly referred to as kilograms per square centimeter is scientifically incorrect but is frequently used in practice, such as on bicycle pumps.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and clarity regarding the units discussed, with no consensus reached on the best sources or definitions. Some participants provide corrections and additional context, but disagreements about the accuracy or relevance of certain units remain unresolved.

Contextual Notes

Some definitions and explanations provided may depend on specific contexts or assumptions that are not fully articulated, such as the historical usage of certain units or the implications of their scientific accuracy.

ShawnD
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There are a few units that I'm interested in understanding a little better; mainly in understanding what they are based on. For example, 1 calorie is the energy to change the temperature of 1kg of water by 1C (IIRC).
Here are the units I don't understand too well.

reaumure - temperature
torr - pressure
bar - pressure

I've already tried to get the info myself. For reaumure, I end up with a bunch of sites in French which doesn't help since I can't read French. Searching for the pressure ones lead me to a bunch of sciences questions/tests posted online.
 
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Originally posted by ShawnD
For reaumure, I end up with a bunch of sites in French which doesn't help since I can't read French

you know it is said that french is the language of love...
hope http://www.britannica.com/eb/article?eu=64484 helps a bit

http://www.npl.co.uk/pressure/punits.html
 
Last edited by a moderator:
Originally posted by ShawnD
There are a few units that I'm interested in understanding a little better; mainly in understanding what they are based on. For example, 1 calorie is the energy to change the temperature of 1kg of water by 1C (IIRC).
Here are the units I don't understand too well.


Small technical detail: the calorie (with a small c) is the heat required to raise one gram of water by one degree C. The Calorie (with a large C) is a "nutritional calorie" which is actually a kilocalorie. THis is what follows your description above, but it is not the calorie used by scientists.

The "bar" has come up in the recent past on a few threads in this forum. IT is defined as the pressure created by "one million dynes of force on one square centimeter." THis is equivalent to 10 Newtons of force on one square centimeter. THis is the same as 100,000 Newtons of force on one square meter which makes one bar exactly 100,000 pascals. The bar is a very convenient unit because one bar is very close to atmospheric pressure (ATM = 1.01 bar).

One bar is also close to the common European pressure unit of kilograms per square centimeter. THis unit is scientifically incorrect, but it is what is written on a lot of bicycle pumps.
 
the Reaumur temperature scale --->
http://www.csc.liv.ac.uk/~frans/COMP101/week6/reaumur.html
 
Last edited by a moderator:
Here are some Wikipedia references for you:

From Wikipedia: Réaumur scale (http://en.wikipedia.org/wiki/R%C3%A9aumur_scale" )
From Wikipedia: Temperature (http://en.wikipedia.org/wiki/Temperature" )
 
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