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Blob
I removed this definition which was added last October unreferenced by an anonymous user:
The unit blob is the inch version of slugs (1 lbf·s²/in).
http://www.designofmachinery.com/MD/ for blobs, also 'slinch' is a gross of blobs, not the inch version of slugs (whoever added it had the conversion wrong, it would have to be 1/12 a slug not 12 slugs)
12 slugs = 1 slinch
1 slugs = 1/12 slinch
, this is because
and
and since 1 foot = 12 inches
do some algebra (multiply all sides by 12) to get
I don't understand the blob. Is there only that one source for the information on the blob? A Google search is useless as there are too many movies or other things named blob. Could 12 blobs = 1 slug(1/12 slugs = 1 blob) as you where saying is the cases of the slinch? Is that the difference between the slinch and the blob?
R00m c (
talk)
03:29, 16 April 2008 (UTC)reply
I removed the statement about the blob because it is not a commonly accepted term. From the reference:
It is unfortunate that the mass unit in the ips system has never been given a name such as the term slug used for mass in the fps system. The author boldly suggests (with tongue only slightly in cheek) that this unit of mass in the ips system be called a blob(bl) to distinguish it more clearly fron the slug (sl)...[1]
As this is the only source, and the author is merely suggesting the use of the term, I don't think it qualifies as a fact.
Djd sd (
talk)
23:57, 23 May 2010 (UTC)reply
Page 21 of Shigley states (regarding the "unit of mass in the ips gravitational system"), "The mass unit lbf.s2/in has no official name.". Shigley also states "there is no abbreviation for slug". — Preceding
unsigned comment added by
119.18.0.134 (
talk)
01:29, 5 October 2011 (UTC)reply
No one has ever used "blob" in this context. This needs to be removed because the topic is confusing enough without this misinformation. — Preceding
unsigned comment added by
66.35.45.68 (
talk)
14:45, 9 September 2015 (UTC)reply
References
^Robert L. Norton, Worcester Polytechnic Institute, Machine Design: An Integrated Approach, Third Edition, Prentice Hall
ISBN0-13-048190-8 Parameter error in {{
ISBN}}: checksum
Relevance
How relevant is that unit slug today, and where and for what business? When there is written about an Australian act of 1960 (no citation!) then this is 53 years ago and Australia is metrificated since 20 years. So slug doesn't seem to be a legal unit for mass in Australia any more. Its coining in the 19th century and the 85 year old textbook paragraph doesn't make it youngeror more relevant.
Since Einstein's claim of 1907, that there is no difference between inert masses and gravitational masses (and energy), a special unit for inertia is not necessary. (Albert Einstein, Jahrbuch der Radioaktivität 1907, p443 + p462, "Über das Relativitätsprinzip und die aus demselben gezogenen Folgerungen")
Is there any relevant modern publication in which a producer, trader or scientist expresses the mass of e.g. a car, a bag of potatoes, an engine or a planet by its intertia in slug?
If there isn't any, it should be mentioned in the article that slug is an old, expired unit out of use and relevance. Its use in concurrence to the pound is over-subtle and obsolet (if one still insists to express something in imperial units).
--
46.115.49.76 (
talk)
15:23, 24 January 2013 (UTC)reply
Engineering Textbooks still use it in the U.S. Example: Engineering Mechanics: Statics, Bedford and Fowler 1999 (and probably subsequent). This is by no means an obsolete unit.
130.76.96.156 (
talk)
21:51, 25 January 2013 (UTC)reply
Slug is relevant as it is the only non-ambiguous and coherent unit of mass in the fps system of units. It is widely used in engineering (particularly aerospace).
203.129.23.146 (
talk)
11:49, 5 July 2013 (UTC)reply
From my experience, slugs are mostly obsolete, but they do still occasionally pop up from time to time. For example, I ended up on this page after having to look up the density of water in slugs/ft3 (1.94 for anyone curious) to plug it into an equation in a building code. However, it is far more common to see pounds-mass (lbm) used than slugs, in both industry and academia.
108.52.118.74 (
talk)
22:31, 29 September 2016 (UTC)reply
Slug value
I reverted the recent edit because the original seems to be correct. See
http://sizes.com/units/slug.htm and the following calculation.
1 slug = mass that accelerates at 1 ft/s2 under 1 pound force = F/a = 1 lbF / (1 ft/s2)
In general, pound can be taken as either pound-force or pound-mass. Labeling the mass version as pound-mass avoids confusion. Wikipedia is for general audiences, not just science and technical ones. -
Fnlayson (
talk)
20:11, 11 December 2016 (UTC)reply
I have several engineering text books that use pound for pound-force and at least one that uses pound for pound-mass. This is largely the authors' conventions and not an official convention. -
Fnlayson (
talk)
20:42, 11 December 2016 (UTC)reply
OK. I have two follow on questions.
How do those text books define the unit "pound" when used as a unit of mass?
What symbol do they use for that unit?
Dondervogel 2
Ones like the Shigley and Mischke book (ref #2 in article), use lb-s2/ft, i.e slug for mass, along with corresponding SI unit, kg. That's all I have. If you don't believe me, whatever. -
Fnlayson (
talk)
02:06, 12 December 2016 (UTC)reply
I am willing to believe that different symbols are used for a
pound of mass outside wikipedia, even though I have not seen these myself. What I question is your assertion that 'lbm' or 'lb_m' is a more appropriate symbol for Wikipedia than the international standard symbol, 'lb'. I asked for a reliable source because that would permit us to discuss the relative merits of the different sources vs the international standard.[1]Dondervogel 2 (
talk)
12:32, 12 December 2016 (UTC)reply
Physicists may not like it, but the kgf creeps into engineering books from time to time. Should we therefore insist on using kgm to disambiguate? Since that is a rhetorical question, why therefore would Wiki invent a lbm symbol when lb has been used for centuries.
Martin of Sheffield (
talk)
23:02, 13 December 2016 (UTC)reply
... and by the way, it has been proposed to hold the discussion centrally, at one of the project pages. I do not have time to start such a discussion, and would not know which project pages are relevant. Instead I propose a centralized discussion at
mosnum.
Dondervogel 2 (
talk)
08:27, 14 December 2016 (UTC)reply
As I stated above that pound is sometimes used for pound-force or pound-mass depending on context. I was not replying to any of your posts. You can always ignore comments. -
Fnlayson (
talk)
12:22, 14 December 2016 (UTC)reply
As lbf is used for pound-force (per IEEE standard), I see no benefit in introducing lbm - use of non-standard symbols leads to unnecessary ambiguity. On the other hand the template does use lbm and lbf, so either we edit the template or we need to define 'lbm'. As a stop-gap measure I will add a link from lbm to pound mass.
Dondervogel 2 (
talk)
18:45, 30 December 2016 (UTC)reply
References
^IEEE Std 260.1™-2004, IEEE Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units)