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Rho
Rho (uppercase Ρ, lowercase ρ or ; el, ρο or el, ρω, label=none) is the 17th letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician letter res . Its uppercase form uses the same glyph, Ρ, as the distinct Latin letter P; the two letters have different Unicode encodings. Uses Greek Rho is classed as a liquid consonant (together with Lambda and sometimes the nasals Mu and Nu), which has important implications for morphology. In both Ancient and Modern Greek, it represents a alveolar trill , alveolar tap , or alveolar approximant . In polytonic orthography, a rho at the beginning of a word is written with a rough breathing, equivalent to ''h'' ( ''rh''), and a double rho within a word is written with a smooth breathing over the first rho and a rough breathing over the second ( ''rrh''). That apparently reflected an aspirated or voiceless pronunciation in Ancient Greek, which led to the various Greek-deri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Density
The density of air or atmospheric density, denoted '' ρ'', is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperature and humidity. At 101.325 kPa (abs) and 20 °C (68 °F), air has a density of approximately , according to the International Standard Atmosphere (ISA). At 101.325kPa (abs) and , air has a density of approximately , which is about that of water, according to the International Standard Atmosphere (ISA). Pure liquid water is . Air density is a property used in many branches of science, engineering, and industry, including aeronautics;Olson, Wayne M. (2000) AFFTC-TIH-99-01, Aircraft Performance FlightICAO, Manual of the ICAO Standard Atmosphere (extended to 80 kilometres (262 500 feet)), Doc 7488-CD, Third Edition, 1993, .Grigorie, T.L., Dinca, L., Corcau J-I. and Grigorie, O. (2010) Aircrafts' Altitude Measurement Using Pressure Information:Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematically, density is defined as mass divided by volume: : \rho = \frac where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure. To simplify comparisons of density across different systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Consonant
In phonetics, liquids are a class of consonants consisting of voiced lateral approximants like together with rhotics like . Etymology The grammarian Dionysius Thrax used the Ancient Greek word (, ) to describe the sonorant consonants () of classical Greek. Most commentators assume that this referred to their "slippery" effect on meter in classical Greek verse when they occur as the second member of a consonant cluster. This word was calqued into Latin as , whence it has been retained in the Western European phonetic tradition. Phonological properties Liquids as a class often behave in a similar way in the phonotactics of a language: for example, they often have the greatest freedom in occurring in consonant clusters. Metathesis Cross-linguistically, liquids are the consonants most prone to metathesis. Spanish In Spanish, /r/ is liable for metathesis. More specifically, /r/ and /l/ frequently switch places: * Lat. ''crocodīlus'' > Span. ''cocodrilo'' “crocodile” * L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rough Breathing
In the polytonic orthography of Ancient Greek, the rough breathing ( grc, δασὺ πνεῦμα, dasỳ pneûma or ''daseîa''; la, spīritus asper) character is a diacritical mark used to indicate the presence of an sound before a vowel, diphthong, or after rho. It remained in the polytonic orthography even after the Hellenistic period, when the sound disappeared from the Greek language. In the monotonic orthography of Modern Greek phonology, in use since 1982, it is not used at all. The absence of an sound is marked by the smooth breathing. The character, or those with similar shape such as , have also been used for a similar sound by Thomas Wade (and others) in the Wade–Giles system of romanization for Mandarin Chinese. Herbert Giles and others have used a left (opening) curved single quotation mark for the same purpose; the apostrophe, backtick, and visually similar characters are often seen as well. History The rough breathing comes from the left-hand half of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
