In physics the density (ρ) of a body is the ratio of its mass (m) to its volume (V), a measure of how tightly the matter within it is packed together[1]. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. In Physics, a physical body (sometimes called simply a body or even an object) is a collection of Masses taken to be one A ratio is an expression which compares quantities relative to each other Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically Matter is commonly defined as being anything that has mass and that takes up space. Its SI units are kilograms per cubic metre (kg/m³). CM3 redirects here If you were looking for the 3rd game in the Cooking Mama series abbreviated as CM3 see here. It is also sometimes given in the cgs units of grams per cubic centimetre (g/cm³). The centimetre-gram-second system ( CGS) is a system of physical units. For other uses of the words gram or gramme see Gram (disambiguation. A cubic centimetre or cubic centimeter (symbol cm3 —the abbreviation cc, though widely used is deprecated is a commonly used unit of Volume
Density is defined by:
Various substances have different densities, and it is this quantity that determines how they interact when mixed together. For example, in SI units the density of lead is 11. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly 35 x 103, that of water is 1 x 103, and that of cork is 0. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Cork material is a Prime-subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree Quercus 24 x 103. The lead has a greater density than water so it sinks; the cork has a smaller density so it floats[2].
In some cases the density is expressed as a specific gravity or relative density, in which case it is expressed in multiples of the density of some other standard material, usually water or air. Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically Relative density, sometimes called specific density, is the Ratio of the Density of a substance to the density of a given reference material
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History
In a well known problem, Archimedes was given the task of determining whether King Hiero's goldsmith was embezzling gold during the manufacture of a wreath dedicated to the gods and replacing it with another, cheaper alloy. Archimedes of Syracuse ( Greek:) ( c. 287 BC – c 212 BC was a Greek mathematician, Physicist, Engineer Hieron II, king of Syracuse from 270 to 215 BC was the illegitimate son of a Syracusan noble Hierocles, who claimed descent from Gelon He was a former A goldsmith is a Metalworker who specializes in working with Gold and other Precious metals usually in modern times to make Jewelry. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has [3]
Archimedes knew that the irregular shaped wreath could be smashed into a cube or sphere, where the volume could be calculated more easily when compared with the weight; the king did not approve of this.
Baffled, Archimedes went to take a bath and observed from the rise of the water upon entering that he could calculate the volume of the crown through the displacement of the water. In Fluid mechanics, displacement occurs when an object is immersed in a Fluid, pushing it out of the way and taking its Allegedly, upon this discovery, Archimedes went running though the streets in the nude shouting, "Eureka! Eureka!" (Greek "I have found it"). As a result, the term "eureka" entered common parlance and is used today to indicate a moment of enlightenment. Eureka ( Greek "I have found it" is an exclamation used as an Interjection to celebrate a discovery
This story first appeared in written form in Vitruvius' books of architecture, two centuries after it supposedly took place. Marcus Vitruvius Pollio (born c 80–70 BC died after c 15 BC was a Roman Writer, Architect and Engineer (possibly praefectus fabrum De architectura ( Latin: "On architecture" is a treatise on Architecture written by the Roman Architect Vitruvius [4] Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time. [5]
Measurement of density
For a homogeneous object, the mass divided by the volume gives the density. If the object has a varying mass, this prescription gives the average density. The mass is normally measured with an appropriate scale or balance; the volume may be measured directly (from the geometry of the object) or by the displacement of a liquid. A weighing scale (usually just "scale" in common usage except in Australian English where "scales" is more common is a Measuring instrument for
A very common instrument for the direct measurement of the density of a liquid is the hydrometer. A hydrometer is an instrument used to measure the Specific gravity (or Relative density) of Liquids that is the ratio A less common device for measuring fluid density is a pycnometer, a similar device for measuring the absolute density of a solid is a gas pycnometer. Another instrument used to determine the density of a liquid or a gas is the digital density meter - based on the oscillating U-tube principle. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of This page is about the physical properties of gas as a state of matter The oscillating U-tube is a technique to determine the Density of Liquids and Gases based on an electronic measurement of the Frequency of oscillation
The density of a solid material can be ambiguous, depending on exactly how it is defined, and this may cause confusion in measurement. A common example is sand: if gently filled into a container, the density will be small; when the same sand is compacted into the same container, it will occupy less volume and consequently carry a greater density. This is because "sand" contains a lot of air space in between individual grains; this overall density is called the bulk density, which differs significantly from the density of an individual grain of sand. Bulk density is a property of powders granules and other "divided" solids especially used in reference to Soil.
Common units
SI units for density are:
- kilograms per cubic metre (kg/m³)
- grams per cubic centimetre (g/cm³)
Units outside the SI
- kilograms per litre (kg/L). CM3 redirects here If you were looking for the 3rd game in the Cooking Mama series abbreviated as CM3 see here. For other uses of the words gram or gramme see Gram (disambiguation. A cubic centimetre or cubic centimeter (symbol cm3 —the abbreviation cc, though widely used is deprecated is a commonly used unit of Volume The litre or liter (see spelling differences) is a unit of Volume. Water generally has a density around 1 kg/L, making this a convenient unit. Water is a common Chemical substance that is essential for the survival of all known forms of Life.
- grams per millilitre (g/mL), which is equivalent to (g/cm³). For other uses of the words gram or gramme see Gram (disambiguation. The litre or liter (see spelling differences) is a unit of Volume.
They also happen to be numerically equivalent to kg/L (1 kg/L = 1 g/cm³ = 1 g/mL).
In U.S. customary units or Imperial units, the units of density include:
- ounces per cubic inch (oz/in3)
- pounds per cubic inch (lb/in3)
- pounds per cubic foot (lb/ft3)
- pounds per cubic yard (lb/yd3)
- pounds per gallon (for U. US customary units, also known in the United States as English units or Imperial units (in reference to the British Empire) (but see English Imperial units or the Imperial system is a collection of units first defined in the British Weights and Measures Act of 1824 This article is about the unit of mass For the unit of force see Pound-force. A cubic inch (plural cubic inches) is a non- SI unit of Volume, equal to the volume of a Cube with sides of one Inch. The pound or pound-mass (abbreviation lb, lbm, or sometimes in the United States #) is a unit of Mass The cubic foot is an imperial and US customary (non- metric) unit of Volume, used in the United States Canada and the United Kingdom A cubic yard is an Imperial / US customary (non- SI non- metric) unit of Volume, used in the United States, Canada and A gallon is a measure of Volume. It is in current use in the United States and still has limited use in many other English-speaking countries S. or imperial gallons) (lb/gal)
- pounds per U. Imperial units or the Imperial system is a collection of units first defined in the British Weights and Measures Act of 1824 S. bushel (lb/bu)
- slugs per cubic foot. A bushel is a unit of dry volume, usually subdivided into eight local Gallons in the systems of Imperial units and U The slug is an English unit of Mass. It is a mass that accelerates by 1 ft/s² when a force of one Pound-force (lbf is exerted on it
Changes of density
In general density can be changed by changing either the pressure or the temperature. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Increasing the pressure will always increase the density of a material. Increasing the temperature generally decreases the density, but there are notable exceptions to this generalisation. For example, the density of water increases between its melting point at 0 °C and 4 °C and similar behaviour is observed in silicon at low temperatures. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14
The effect of pressure and temperature on the densities of liquids and solids is small so that a typical compressibility for a liquid or solid is 10–6 bar–1 (1 bar=0. In Thermodynamics and Fluid mechanics, compressibility is a measure of the relative volume change of a Fluid or Solid as a response The bar (symbol bar) decibar (symbol dbar) and the millibar (symbol mbar, also mb are units of Pressure. 1 MPa) and a typical thermal expansivity is 10–5 K–1. Thermal Expansion is the tendency of matter to change in Volume in response to a change in temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic
In contrast, the density of gases is strongly affected by pressure. Boyle's law says that the density of an ideal gas is given by
where R is the universal gas constant, P is the pressure, M the molar mass, and T the absolute temperature. Boyle's law (sometimes referred to as the Boyle-Mariotte law) is one of several Gas laws and a special case of the Ideal gas law. These four properties that constitute an ideal gas can be easily remembered by the acronym RIPE which stands for - R andom Motion (molecules are in constant random motion Relationship with the Boltzmann constant The Boltzmann constant kB (often abbreviated k) may be used in place of the gas constant by working Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) Thermodynamic temperature is the absolute measure of Temperature and is one of the principal parameters of Thermodynamics.
This means that a gas at 300 K and 1 bar will have its density doubled by increasing the pressure to 2 bar or by reducing the temperature to 150 K. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The bar (symbol bar) decibar (symbol dbar) and the millibar (symbol mbar, also mb are units of Pressure. The bar (symbol bar) decibar (symbol dbar) and the millibar (symbol mbar, also mb are units of Pressure. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic
Iridium is the densest known substance at standard conditions for temperature and pressure. Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 In Physical sciences standard conditions for temperature and pressure are Standard sets of conditions for experimental measurements to allow comparisons to be made
Density of water
| Temp (°C) | Density (g/cm3) |
|---|---|
| 100 | 0. 9584 |
| 80 | 0. 9718 |
| 60 | 0. 9832 |
| 40 | 0. 9922 |
| 30 | 0. 9956502 |
| 25 | 0. 9970479 |
| 22 | 0. 9977735 |
| 20 | 0. 9982071 |
| 15 | 0. 9991026 |
| 10 | 0. 9997026 |
| 4 | 0. 9999720 |
| 0 | 0. 9998395 |
| −10 | 0. 998117 |
| −20 | 0. 993547 |
| −30 | 0. 983854 |
| The density of water in grams per cubic centimeter at various temperatures in degrees Celsius [6] The values below 0 °C refer to supercooled water. |
|
See Water Density
Density of air
| T in °C | ρ in kg/m³ (at 1 atm) |
|---|---|
| –10 | 1. Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as The Celsius Temperature scale was previously known as the centigrade scale. The Standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of Pressure (symbol atm 342 |
| –5 | 1. 316 |
| 0 | 1. 293 |
| 5 | 1. 269 |
| 10 | 1. 247 |
| 15 | 1. 225 |
| 20 | 1. 204 |
| 25 | 1. 184 |
| 30 | 1. 165 |
Density of solutions
The density of a solution is the sum of the mass (massic) concentrations of the components of that solution. Mass (massic) concentration of a given component ρi in a solution can be called partial density of that component.
Densities of various materials
| Material | ρ in kg/m³ | Notes |
|---|---|---|
| Interstellar medium | 10-25 − 10-15 | Assuming 90% H, 10% He; variable T |
| Earth's atmosphere | 1. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five 2 | At sealevel |
| Aerogel | 1 − 2 | |
| Styrofoam | 30 − 120 | From |
| Cork | 220 − 260 | From |
| Water | 1000 | At STP |
| Plastics | 850 − 1400 | For polypropylene and PETE/PVC |
| The Earth | 5515. Aerogel is a low-density solid-state material derived from Gel in which the liquid component of the gel has been replaced with gas Styrofoam is a trademark for polystyrene Thermal insulation, a material manufactured by Dow Chemical Company. Cork material is a Prime-subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree Quercus Water is a common Chemical substance that is essential for the survival of all known forms of Life. In Physical sciences standard conditions for temperature and pressure are Standard sets of conditions for experimental measurements to allow comparisons to be made Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products Polypropylene or polypropene ( PP) is a Thermoplastic Polymer, made by the Chemical industry and used in a wide variety of applications Uses PET can be semi-rigid to rigid depending on its thickness and is very lightweight EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 3 | Mean density |
| Copper | 8960 | Near room temperature |
| Lead | 11340 | Near room temperature |
| The Inner Core | ~13000 | As listed in Earth |
| Uranium | 19100 | Near room temperature |
| Iridium | 22500 | Near room temperature |
| The core of the Sun | ~150000 | |
| Atomic nuclei | ~3 × 1017 | As listed in neutron star |
| Neutron star | 8. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed The inner core of the Earth, its innermost layer as detected by seismological studies, is a primarily solid Sphere about in radius only about 70% EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed The Sun (Sol is the Star at the center of the Solar System. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom A neutron star is a type of remnant that can result from the Gravitational collapse of a massive Star during a Type II, Type Ib or Type A neutron star is a type of remnant that can result from the Gravitational collapse of a massive Star during a Type II, Type Ib or Type 4 × 1016 − 1 × 1018 | |
| Black hole | 2 × 1030 | Mean density inside the Schwarzschild radius of an earth-mass black hole (theoretical) |
References
- ^ About.com: What is Density?
- ^ Oxford Illustrated Encyclopedia: The Physical World p. A black hole is a theoretical region of space in which the Gravitational field is so powerful that nothing not even Electromagnetic radiation (e The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is a characteristic Radius associated with every Mass. 87
- ^ Archimedes, A Gold Thief and Buoyancy - by Larry "Harris" Taylor, Ph. D.
- ^ Vitruvius on Architecture, Book IX, paragraphs 9-12, translated into English and in the original Latin.
- ^ The first Eureka moment, Science 305: 1219, August 2004. Fact or Fiction?: Archimedes Coined the Term "Eureka!" in the Bath, Scientific American, December 2006.
- ^ Lide, D. R. (Ed. ) (1990). CRC Handbook of Chemistry and Physics (70th Edn. ). Boca Raton (FL):CRC Press.
Books
- Fundamentals of Aerodynamics Second Edition, McGraw-Hill, John D. Anderson, Jr.
- Fundamentals of Fluid Mechanics Wiley, B. R. Munson, D. F. Young & T. H. Okishi
- Introduction to Fluid Mechanics Fourth Edition, Wiley, SI Version, R. W. Fox & A. T. McDonald
- Thermodynamics: An Engineering Approach Second Edition, McGraw-Hill, International Edition, Y. A. Cengel & M. A. Boles
See also
External links
- Glass Density Calculation - Calculation of the density of glass at room temperature and of glass melts at 1000 - 1400°C
- List of Elements of the Periodic Table - Sorted by Density
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