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graphic negârik Fr.: graphique (Adj.) Pertaining to the use of diagrams, graphs, mathematical curves, or the like. |
graphite gerâfit (#) Fr.: graphite A particular crystalline form of → carbon occurring as a soft, black,
lustrous mineral. The carbon atoms in graphite are strongly bonded together in sheets.
Because the bonds between the sheets are weak, other atoms can easily fit between them,
causing graphite to be soft and slippery to the touch. Graphite conducts electricity
and is used in lead pencils and electrolytic anodes, as a lubricant, and as a
moderator in nuclear reactors. If graphite is subjected to high pressure, it
will be transformed into → diamond. From Ger. Graphit, from Gk. graph(ein) "to write, draw," so called because it was used for pencils, → graph + -it a suffix of chemical compounds, equivalent to E. -ite. |
grating turi, ~ -e parâš (#) Fr.: réseau Same as → diffraction grating. M.E. grating, M.L. grata "a grating," variant of crata, from crat-, stem of cratis "wickerwork." Turi, from tur "fishing net, net, snare," variants târ "thread, warp, string," tâl "thread" (Borujerdi dialect), cognate with tanidan, tan- "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- to stretch, extend;" Skt. tan- to stretch, extend;" tanoti "stretches," tantram "loom;" tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch"). |
grating angle zâviye-ye turi (#) Fr.: angle de réseau The angle between the incident optical beam and the normal to the grating. It is the angle to which the grating must be set to place the desired wavelength at the center of the detector. |
grating efficiency kârâyi-ye turi (#) Fr.: efficacité de réseau The measure of the light intensity diffracted from a grating. → grating; → efficiency. |
grating groove šiyâr-e turi (#) Fr.: trait du réseau, sillon ~ ~ One of thousands of long, narrow indentations in the surface of a → diffraction grating. |
gravitate gerânidan (#) Fr.: graviter To move or tend to move under the influence of gravitational force. From L. gravitatus, p.p. of gravitâre, from gravis "heavy," → gravity. Gerânidan, infinitive of gerân, → gravity. |
gravitation gerâneš (#) Fr.: gravitation 1) The universal phenomenon of attraction between material bodies.
→ Newton's law of gravitation. Verbal noun of → gravitate. |
gravitational gerâneši (#) Fr.: gravitationnel Of or relating to or caused by → gravitation. Adj. of → gravitation. |
gravitational acceleration šetâb-e gerâneši (#) Fr.: accélération gravitationnelle The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R^{2}, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s^{-2}. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity. → gravitational; → acceleration. |
gravitational attraction darkešeš-e gerâneši Fr.: attraction gravitationnelle The force that pulls material bodies toward one another because of → gravitation. → gravitational; → attraction. |
gravitational collapse rombeš-e gerâneši (#) Fr.: effondrement gravitationnel Collapse of a mass of material as a result of the mutual → gravitational attraction of all its constituents. → gravitational; → collapse. |
gravitational constant pâyâ-ye gerâneši (#) Fr.: constante gravitationnelle A fundamental constant that appears in → Newton's law of gravitation. It is the force of attraction between two bodies of unit mass separated by unit distance: G = 6.673 x 10^{-8} dyn cm^{2} g^{-2} or 6.673 x 10^{-8} cm^{3}s^{-2}g^{-1}, or 6.673 x 10^{-11} N m^{2} kg^{-2} or 6.673 x 10^{-11} m^{3}s^{-2}kg^{-1}. It was first measured in 1798 by Henry Cavendish (1731-1810), 71 years after Newton's death. Same as the → Newtonian constant of gravitation. → gravitational; → constant. |
gravitational contraction terengeš-e gerâneši Fr.: contraction gravitationnelle Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force. → gravitational; → contraction. |
gravitational encounter ruyâruyi-ye gerâneši Fr.: rencontre gravitationnelle An encounter in which two moving bodies alter each other's direction and velocity by mutual → gravitational attraction. → gravitational; → encounter. |
gravitational energy kâruž-e gerâneši Fr.: énergie gravitationnelle Same as → gravitational potential energy. → gravitational; → energy. |
gravitational equilibrium tarâzmandi-ye gerâneši (#) Fr.: équilibre gravitationnel The condition in a celestial body when gravitational forces acting on each point are balanced by some outward pressure, such as radiation pressure or electron degeneracy pressure, so that no vertical motion results. → gravitational; → equilibrium. |
gravitational field meydân-e gerâneši (#) Fr.: champ gravitationnel The region of space in which → gravitational attraction exists. → gravitational; → field. |
gravitational force niru-ye gerâneši (#) Fr.: force gravitationnelle The weakest of the four fundamental forces of nature. Described by → Newton's law of gravitation and subsequently by Einstein's → general relativity. → gravitational; → force. |
gravitational instability nâpâydâri-ye gerâneši (#) Fr.: instabilité gravitationnelle The process by which fluctuations in an infinite medium of size greater than a certain length scale (the Jeans length) grow by self-gravitation. → gravitational; → instability. |
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