Talk:Density

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The article says that densities should be specified in kg/m3 - yet the table of sample densities are in g/cm3. This is not a good thing! The numbers need to be 1000 times larger and the units at the top of the table changed.

Would someone please add an entry for ice? Thanks! Aspie 23:38, 4 October 2005 (UTC)

SteveBaker says: The generally accepted figure is 917 kg/m3 - but density varies with temperature. I presume the table in the article is for densities at room temperature - and you can't say what the density of ice is at room temperature! but, it is possible. hahaha

density=mass/volume.< remember that...if u can..(rose)penis

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andre **** you. **** your mother, dog, father, sister, brother and all your family. Water isn't really defined to have density 1 is it? That's a schoolboy definition. --drj

Mayhaps, I certainly was a schoolboy once :-) The fact that one litre of water weighs exactly one kilogram os no accident however. The SI units were chosen carefully, although i know not if the metre or the kilogram was defined first (my money is on the metre), the relation between them is indeed found through the density of water (at 4 degrees celsius if memory serves correctly). --Anders Törlind.

Oh, by the way, is the kilogram still defined as the lump of platinum they hold in Paris, or is it defined as a certain number of atoms of something? --Anders Törlind

I wondered about this recently. My research confirms what kilogram says. There is a standard mass made from platinum/rhodium. I guess it is too difficult to define it as the number of atoms of something. --drj

Meter was defined 1791 by the French Academy of Science first the kilogramm 1889, so meter was a way earlier defined (but it depends what definition of meter or kilogramm you prefer to be the first correct one). The definition of meter has changed a bit over time, the definition of kilogramm is the same since 1889. Information taken from: http://physics.nist.gov/cuu/Units/current.html -- Tom B.

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I believe that the metere was originally defined to be 1x10^-6 of the distance from the equator to the north pole via a line that went through Paris, this was mesured incorrectly at the time, so the distance is somewhat different. The other units as far as I know are based on that. The kilogram was originally based on a cubic decimeter of water, but that is much too variable to be used as a reference.-- mike dill

Actually, one ten-millionth, which is 10^-7. (I fixed your tags.) Vicki Rosenzweig

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Do you have the reference for the platinum density of 21.09? According to http://hypertextbook.com/facts/2004/OliviaTai.shtml, the density is 21.45 and they list 5 references. When I Google platinum density, the first entry webelements.com (another wiki) agrees with 21.09, but going on down the list several pages, everyone else says from 21.4 to 21.5. If you change to 21.45 then change the Wikipedia platinum article also. Art LaPella 05:04, Aug 22, 2004 (UTC)

I have checked the CRC Handbook of Chemistry and Physics (60th edition, page B-106) and it gives 21.45 at 20 degC: so have changed here and on the platinum page. --GPoss 06:36, Aug 22, 2004 (UTC)

For the record, the 21.09 value apparently originates from Lange's Handbook of Chemistry, McGraw-Hill (also cited by WebElements, and standing rather lonely among the other references). Femto 12:00, 14 July 2005 (UTC)

Contents 1 Osmium vs Iridium 2 Table salt density 3 density of materials of equal volume 4 Nonsense 5 I need help!! 6 Unit term style 7 weak width 8 help 9 in other language : french 10 Density Rocks! 11 Measurement of density 12 iVan asks:

[edit] Osmium vs Iridium

It seems the articles for Osmium and Iridium give different values for the density of Osmium compared to the value in the density table, affecting the order of the elements in the table. Apparently Osmium should be listed at 22661 kg/m³ rather than 22610 kg/m³. --Vinsci 14:48, 4 Apr 2005 (UTC)

--- It looks like those two articles now both explain that the difference in density between Osmium and Iridium is so small that it takes theoretical calculations of density to tell the difference between them. This article is far too definitive about Iridium being the densest. The language should be loosened somewhat.

[edit] Table salt density

What is the density of table salt (in grams per cubic centimeter)?

Can anyone put more information on this page i need more information!! thnx :D

• Please see the sodium chloride page, to find your answer.

[edit] density of materials of equal volume

[edit] Nonsense

There is a non sequitur at the end of the "Measurement of density" section: "this site is extremly good for finding scientific info." Is this supposed to be turned into something or should it just be deleted? Epugachev 06:32, 28 February 2006 (UTC)

Gone. Femto 12:05, 28 February 2006 (UTC)

[edit] I need help!!

Does anyone know why egg float in the salt water and how?

         The salt in water is much denser than the yolk in the egg. Thus making it float. 

04:23, 16 February 2007 (UTC)

"Relative density(specific gravity) of salty water is higher than normal water. For example salt water is ~1.025 whereas water is 1. Arcemedaes principle says that the net upthrust on an object = the weight of fluid displaced. i.e. in salty water this is a number larger than the weight of the egg. As a side note, you can tell if an egg is bad because it floats in fresh water. This happens because air travels to the bacteria through the porous shell and they respire, lowering the overall density.(no citations, I don't have any)" (James Pipe 19:04, 28 February 2007 (GMT))

[edit] Unit term style

Regarding the recent 'corrections', neither style is incorrect. The term a · b⁻¹ is equivalent to a/b. While this makes little difference for kg/L, I think in the general case a consistent exponential style kg · m⁻¹ · s⁻² would be preferable over a proper fraction . Femto 17:44, 28 March 2006 (UTC)

HOW DO YOU MEASURE DENSITY ??? and what tool do you use??

[edit] weak width

how do you measure density and what tool do you use??

[edit] help

density and the knetic theory

[edit] in other language : french

The link to the french page is wrong : in french the "densité" stands for a ratio and doesn't have a unit whereas is has one in english. The link should led to http://fr.wikipedia.org/wiki/Masse_volumique, which is what the french call "density".

[edit] Density Rocks!

Yo man, Density is such an easy subject to talk about and you guys got a lot of great information on it. You really elped me out with my science essay.

                        Thanks,
                              
                               Santa!

[edit] Measurement of density

The section on the measurement of density doesn't make sense

It currently reads

For substances other than solids, the density can be found by measuring the dry weight ( Wd ), the wet weight ( Ww) and submersed weight ( Ws), usually in water.

The phrase "For substances other than solids" surely means liquids and gases whose density is certainly not measured by the immersion method described and the term wet weight is not defined.

I had changed this to

For irregularly shaped solids, the density can be found by measuring the dry weight ( Wd ), and the weight when the object is submersed ( Ws), usually in water.

Leaving aside the fact that submersed is not a word, this describes the Archemedian method of measuring the density of an irregularly shaped object.

Comments please

John Loveday

Yadevol 09:32, 19 February 2007 (UTC)yadevol

Now removed this since nobody respondedYadevol 15:46, 24 February 2007 (UTC)yadevol

[edit] iVan asks:

does anyone know how to increase/decrease density? —The preceding unsigned comment was added by 138.123.134.102 (talk) 13:34, 23 February 2007 (UTC).

You can do this by changing the pressure Yadevol 15:46, 24 February 2007 (UTC)yadevol

I have now added a section on thisYadevol 16:22, 24 February 2007 (UTC) yadevol

how is density related to gravity?

The relationship between density and gravity is illegitimate. Considering their popularity, it's amazing how they've eluded tabloids all this time. -71.193.200.17 03:30, 22 March 2007 (UTC)