Density

This topic covers Density -- Claimed by Ritvik Khanna, M08 Dr. Greco Spring 2016

The Main Idea

Density can be simply defined as the relative compactness of a substance. The consistency of the matter at hand can be quantified by mass per unit volume. The density, also called the volumetric mass density, of a substance is denoted by the greek symbol ρ (the lowercase Greek letter rho) but sometimes it can also be represented by the Latin letter D. The density of materials varies, different materials will have different densities. For instance, osmium and iridium are different elements and therefore have different densities. Osmium has a density of 22.59 g/cm^3 while iridium has a density of 22.42 g/cm^3. Also the density of a material can be related to the materials buoyancy, packaging, and purity.

A Mathematical Model

Mathematically density is defined as mass divided by volume.

[math]\displaystyle{ \rho = \frac{m}{V}, }[/math]

Density = Mass / Volume

In this equation ρ is the density, m is the mass, and V is the volume. In this equation mass is divided by volume and in the US oil and gas industry sometimes density is referred to as weight per unit volume. This is technically incorrect as this quantity is actually called specific weight. The mass can be expressed in grams [g] or kilograms [kg], and the volume is measured in liters [L], cubic centimeters [cm^3], or milliliters [mL].

A Computational Model

define mass and volume. ex: m = 500 vol = 40 density = m / vol

Examples

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Connectedness

Density is important in construction of biomaterials that could potentially have clinical applications.

History

Archimedes in 250 B.C. "discovered" density. He suspected that he was being cheated on by the metal craftsmen who had constructed his golden crown. Archimedes suspected that the craftsman was using a sizeable amount of silver with his gold crown, which is cheaper, and ultimately an insult to the king. Archimedes put the crown that the craftsmen had created as well as a crown of pure gold both into a bathtub full of water. He measured the amount of water that was in excess and confirmed his suspicions. He then proceeds to chant "Eureka! Eureka!" in the streets.

See also

Mass and Volume Pages.

Further reading

physics.info/density

External links

http://www.ssc.education.ed.ac.uk/BSL/chemistry/densityd.html

References

Chabay & Sherwood: Matters and Interactions -- Modern Mechanics Volume 1, 4th Edition