Depending on which guide you’re following. The CERN styleguide, for example, specifies that the plural is never used.
kelvin
Spell out on first mention; note the lower-case k (all SI units are lower case when spelled out); can be abbreviated to K in subsequent mentions. And note that it is always kelvin, even when plural (not kelvins or degrees kelvin).
So one thousand kelvins is 1K K. Got it.
1 kK would be correct. Lowercase for the modifier, and it binds to the unit, not the number.
Not 1k K? That seems more correct.
We have kilograms and kilometers, so presumably we can also have kilokelvins.
Colloquially, people will sometimes say 1k to mean 1000 of something, but in SI the modifier binds to the unit. nm, mm, km, kPa, etc.
So in SI, 1,000 kilometers is 1kkm (or 1 kKM or 1 kKM or 1kkm)? I personally would type that as 1k km. Surely it’s 1 thousand (1k) Kelvin (K), so 1k K. The small k modifies the 1 and the K specifies the unit of measure. I would also type 1km, but only if the “1” isn’t modified further.
I don’t think SI allows multiple modifiers. You would write 1 Mm (one megameter) or 1000 km. The m for meter is always lowercase, while the M for mega is uppercase. On the other hand, the k for kilo is lowercase and the K for kelvin is uppercase.
Various style guides aside, I still prefer to use the ° symbol for degrees of kelvin bacon.
Units of medicine dosage are almost always specified in milligrams, or mg, even when there are 1000 of them. Thus, 1000 mg of acetaminophen, never 1g of acetaminophen.
When my doctor once remarked that 1000 mg of apap is 1g, I pointed out that it was actually 1 kilomilligram.
Isn’t there some rule that the units for positive powers of 10 (kilo, mega, giga, etc.) are abbreviated with a capital letter, while the units for negative powers of 10 (centi, milli, micro, etc.) are abbreviated with a lower-case letter?
Likewise, architectural drawings in metric countries are always specified in millimeters, even for a 10 km bridge. I think this reduces the chance for error when the unit is inevitably left off somewhere or is incorrectly labeled (example).
k for kilo is always lowercase, but above that I think it’s always uppercase. M, G, and T, certainly. The larger ones aren’t in common enough use that I’ve seen a pattern.
In building bridges or space telescopes, precision matters. Specifying a bridge in mm enables the architect to indicate, for example, that the bridge is actually 100 00187 mm long.
You see ! This is why I put the degree symbol in to avoid confusion !
I think that with that level of precision, you are going to need to figure in the temperature as well.
There’s an interesting argument about scale measurements versus measurements in units, and temperatures in kelvins are measurements in units. But Fahrenheit and Celsius temperatures are scale temperatures that reference points on a scale that could be as arbitrary as its inventors wish. The Beaufort wind scale is another example of a scale measurement as opposed to one in units.
I do a lot with temperature, and the scale temperatures are a royal pain in the ass sometimes. You might read that the temperature was 18 Fahrenheit degrees plus or minus 2 degrees, and see that converted to -7.8 Celsius degrees plus or minus -16.7 degrees. There’s no way you’ll ever see the cube of a scale temperature. Though I did find one graph in the literature that was the base ten log of the Fahrenheit scale temperature (which fit the range of interest onto the graph fairly neatly).
Imagine if we said most things are bigger than an inch in size, so we’re going to start the size scale’s zero at what we would today call one inch. In the old system this here metal rod is one quarter inch in diameter, but in the new system it becomes -3/4 inches.
The biggest thing a degree symbol does in a temperature in kelvins is to flag the whole thing as suspect.
The Beaufort scale seems conceptually more like Kelvin to me. It starts from an “absolute zero” point, still air. It’s essentially windspeed - it’s just that it’s non-linear.
I think more important is that kelvins are actual units. For example, they can be added, taken to powers, multiplied or divided (think heat transfer coefficient). To do that with scale temperatures requires a workaround. Beaufort numbers are non-linear and they are therefore non-proportional even if the scale contains a zero. There’s no significance to the sum or square root of a Beaufort number.
There’s a tradition of handling scale temperatures with, often, unit terminology. For example, most unit converting programs will also take scale temperatures. But the workaround involved can get pretty nutty. I often do things with for example a temperature change of about 0.1 K, which is also a change of 0.1 degrees on the Celsius scale. But a unit conversion program will typically announce that my 0.1 Celsius degrees is 32.18 Fahrenheit degrees, which is pathologically nuts.
Yeah, absolute scales are better at demonstrating how hot “cold” temperatures actually are. If you go from 10 to 20 Fahrenheit, you are not doubling the temperature. I still remember this being hard to grasp by some of my fellow high school physics students forever ago.
The first images captured by Webb will be released today at 10:30 a.m. EST (1530 GMT) via NASA’s James Webb Space Telescope blog.
Cool ! Here’s the quick link again