Kelvins?
Kelvins?
(OP)
It was recently brought to my attention that the plural of the SI temperature unit "kelvin" is "kelvins." I always thought that the singular and plural pronunciation were the same, i.e., 280 kelvin, not 280 kelvins. Am I alone in being surprised by this? Through six years of undergrad and grad school I never once heard anyone utter the word "kelvins" (although I heard plenty of people say "degrees kelvin," which I know is incorrect).
I am struggling to accept this and wonder what some of you think.
I am struggling to accept this and wonder what some of you think.





RE: Kelvins?
°F & °C are never expressed as Fahrenheits or Centigrades.
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RE: Kelvins?
RE: Kelvins?
"Fahrenheits" is not used because the plural of degree is used instead, as in "1 degree Fahrenheit" and "10 degrees Fahrenheit." Same for Celsius. "Degree," however, is not used with kelvin (note also that the lowercase should be used when spelling out).
Several websites and dictionaries (including Encarta) give the plurar as kelvins. See, for example:
http
which explicitly spells this out.
This is especially embarrassing to me because I recently corrected a colleague who used "kelvins" and was nearly 100% sure that the plural was simply kelvin. After I did some research, it turns out he was right. I hate it when that happens.
RE: Kelvins?
Still, it just don't sound right.
RE: Kelvins?
It is a singular reading. (a singular point on the kelvin scale)
The term kelvin is pointing out the "Scale" being used.
I am not sure if Degree(s) should be used with the kelvin scale or not, but a singular number isn't a plural unless it is denoting a quantity, not a scale location.
To denote a quantity you would have to use "Degree(s)", but once again the plural would be on Degree and not kelvin.
I think they need to go back and revise the reference again (2/00)
First they say: Kelvin scale, then they truncate the reading to 280 kelvin or 280 K. Which doesn't use degrees, but still only locates a "single" point on the scale.
(The last time I delt with this was in Advanced Chemistry 1968, so maybe I'm wrong...but I'm not changing now)
RE: Kelvins?
There are 100 kelvins between the temperatures at which water freezes and boils. Note that while Celsius, Fahrenheit and Rankine degrees are capitalized, kelvins are not. Would this mean that a plural is thus acceptable ?
RE: Kelvins?
Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein
RE: Kelvins?
RE: Kelvins?
The official site for the SI is the BIPM in France. Here are two links that show the plural as kelvins.
http:
http://www1.bipm.org/utils/en/pdf/si-brochure.pdf
All SI units that are spelled are NOT capitalized. If the unit is derived from a proper noun (e.g. a person's name), then the SYMBOL is capitalized (e.g. N for newton or K for kelvin).
The only SI units that are irregular (i.e. do not use an "s" for plural) are lux, hertz, and siemens.
According to NIST SP 811, available at:
http://ts.nist.gov/ts/htdocs/200/202/mpo_pubs.htm
derived units usually are singular. For example, 3 m2 · K / W is said "3 square meter kelvin per watt. But, a single unit like 3 kPa is 3 kilopascals, although 3 kilopascal is acceptable. So stevenal's examples are both correct.
Regards,
Cory
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