Talk:Kip (unit)
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[edit] Force or mass?
The kip, unlike the pound on which it is based, is almost always a unit of force rather than a unit of mass. It was used very little if at all when the absolute fps system (which does not include pounds-force) dominated in science and engineering. It is mostly used by people who use, as calculation aids, either the engineering fps system or the gravitational fps system, both of which do include pounds force (the engineering system includes pounds mass as well).
The name "kip-force" for the unit of force, and the symbol kipf for that unit, are almost never seen outside lists of conversion factors. Note that you do see phrases such as "a two-kip force is applied"—but in that situation, it is the word force used as a noun and the word kip used as an adjective, not the other way around with kip as the noun and force as the adjective in the unit name used by Urhixidur.
- One clue is to see if it would make sense to substitute "newton" for "kip" in the phrase, e.g. "a two-newton force is applied." Since the newton is always a unit of force, there is no need to identify it as a "newton-force".
- Another clue sometimes found is the article "a" or "the" sometimes found in front of the adjectival kip, as "a two-kip" in my example. We don't normally use indefinite articles in front of definite numbers that are not part of an adjective phrase with their units of measur.
- A weaker clue is the fact that it is "kip" rather than "kips" in this phrase; that is weaker because the word kip has the symbol kip as well.
- Therefore, even if kip (as a symbol, rather than a word) were used as the noun and force as an adjective, it might still be "two kip force" rather than "two kips force"; however, if a hyphen is used in that case, it should come as "two kip-force" between kip and force, and not between the number and the symbol kip.
Textbooks also normally list conversion factors from kip to newtons, and not from kip to kilograms. (That isn't necessarily a reliable guide, however, since many of those textbooks currently being written are written by authors too stupid to understand that pounds are units of mass—that is something that has changed in the past few decades; the people who used "poundals" were unlikely to make this particular mistake.)
The name "kip-force" for the unit of force, and the symbol kipf for that unit, are also never seen even in lists of conversion factors contained in books or web sites which actually use these units, not merely just listing them in a table of conversion factors.
Gene Nygaard 09:11, 29 Dec 2004 (UTC)
Addendum:
NIST Guide for the Use of the International System of Units (SI), Appendix B: Conversion Factors This only lists kip as a unit of force, not as a unit of mass. There is no kip as a unit of mass listed here--that is far too rare to merit inclusion in this very comprehensive list of conversion factors. Contrast that with the use of "pound" and "pound-force" in this table, where the distinction is clearly maintained in both their names and their symbols, not just in their entries as stand-alone units but also in all the units in which one or the other or both are part of a combination of units. Gene Nygaard 09:40, 29 Dec 2004 (UTC)
Note also that all three External Links that were here before I added the one to NIST refer to the "kip" only as a unit of force, not as a unit of mass. Gene Nygaard 11:12, 29 Dec 2004 (UTC)
- A strong argument indeed. The Britannica says nothing on the subject. The Webster Reference Dictionary, however, says the kip is « a unit of deadweight equal to 1000 pounds and used to compute shipping charges ». So we do indeed have two different units bearing the same name!
- Urhixidur 18:39, 2004 Dec 29 (UTC)
