Why is Rankine Measured in Degrees?

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Discussion Overview

The discussion revolves around the measurement of Rankine in degrees, particularly in comparison to the Kelvin scale. Participants explore the historical and conceptual reasons behind the use of degrees in Rankine despite it being an absolute temperature scale, as well as the implications of temperature scale definitions.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants note that while Kelvin is an absolute scale and does not use degrees, Rankine is typically associated with degrees, leading to questions about the rationale behind this distinction.
  • One participant suggests that the degree designation in Rankine may relate to the step size of the scale, which they believe is significant.
  • Another participant mentions that the use of °K for Kelvin is no longer standard since 1967, indicating a shift in how temperature scales are denoted.
  • There is a mention of the Rankine scale being based on the Fahrenheit scale, with specific reference to the freezing point of water defined at 491.67 °R.
  • Participants express surprise at the existence of various temperature scales, including historical ones like the Delisle scale, and share insights about the evolution of the Celsius scale.
  • One participant reflects on the discrepancies in temperature definitions, particularly between Celsius and Kelvin, indicating a lack of clarity on the historical changes in definitions.

Areas of Agreement / Disagreement

Participants do not reach a consensus regarding the reasons for Rankine being measured in degrees. Multiple viewpoints are presented, and the discussion remains unresolved.

Contextual Notes

Limitations include the historical context of temperature scales, the evolution of definitions, and the lack of clarity on the implications of using degrees in absolute temperature scales.

gfd43tg
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I know kelvin has no degrees because it is an absolute scale, but I've never seen rankine not be associated with a degree, yet it is also an absolute scale. Anyone know why this is?
 
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I think it should as well be °K because the degree basically refers to the step size which matters a lot. However, it simply doesn't make a difference. Most likely it's for historical reasons (which I don't know).
 
fresh_42 said:
I think it should as well be °K

it is just Kelvin, no degrees

since 1967, no longer written °K

that I also didn't know ... thought it has always just been just Kelvinlive and learn :smile:
 
Maylis said:
but I've never seen Rankine not be associated with a degree

hadn't even heard Rankine temp scale... must have been in very limited use

Another absolute temperature scale is the Rankine (°R) scale, once used by engineers in the United States and based on the Fahrenheit (°F) temperature scale, with the freezing point of water defined as 491.67 °R. A degree Rankine, like a degree Fahrenheit, is 5/9 of a kelvin or degree Celsius.
D
 
davenn said:
it is just Kelvin, no degrees
Yes, but I still think (meant as an opinion, not as an assumption) °K would be more accurate.

live and learn :smile:
Yes! And I've read about many other scales I've never heard of before, too. I always thought Kelvin, Celsius, Fahrenheit and Réaumur were all.

And I learned that Celsius was an upside down scale in its beginning, i.e. freezing at 100°C, evaporation at 0°C! It has been changed by Linné shortly after Celsius' death. And the Russian also used a turned scale in the 19th century: °D (Delisle).

And I learned that the triple point of water defines Kelvin. I've always wondered where the discrepancy between 273,15°C and 273,16°C comes from. I mistakenly thought it had something to do with the change of definition since my school days.
 
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