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variational principle parvaz-e varteši Fr.: principe variationnel Any of the physical principles that indicate in what way the actual motion of a state of a mechanical system differs from all of its kinematically possible motions or states. Variational principles that express this difference for the motion or state of a system in each given instant of time are called → differential. These principles are equally applicable to both → holonomic and → nonholonomic systems. Variational principles that establish the difference between the actual motion of a system during a finite time interval and all of its kinematically possible motions are said to be → integral. Integral variational principles are valid only for holonomic systems. The main differential variational principles are: the → virtual work principle and → d'Alembert's principle. → variational; → principle. |
variety vartiné Fr.: variété 1) The quality or state of having different forms or types. M.Fr. variété, from L. varietatem (nominative varietas) "difference, diversity; a kind, variety, species, sort," from varius, → various. Vartiné, from vartin, → various, + noun/nuance suffix -é. |
Varignon's theorem farbin-e Varignon Fr.: théorème de Varignon The → moment of the resultant of a → coplanar system of → concurrent forces about any center is equal to the algebraic sum of the moments of the component forces about that center. Named after Pierre Varignon (1654-1722), a French mathematician, who outlined the fundamentals of statics in his book Projet d'une nouvelle mécanique (1687). |
various vartin Fr.: varié 1) Of different kinds, as two or more things; differing one from another. M.Fr. varieux and directly from L. varius "changing, different, diverse," → vary. Vartin, from vart "change," present stem of vartidan, → vary, + adj. suffix -in. |
vary vartidan Fr.: changer, varier 1) To undergo change in form, substance, appearance, etc. M.E. varien, from O.Fr. varier, from L. variare "change, alter, make different," from varius "variegated, different, spotted." Vartidan "to change," from Mid.Pers. vartitan "to change, turn" (Mod.Pers. gardidan "to turn, to change"); Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend." |
vector bordâr (#) Fr.: vecteur Any physical quantity which requires a direction to be stated in order to define it completely, for example velocity. Compare with → scalar. From L. vector "one who carries or conveys, carrier," from p.p. stem of vehere "carry, convey;" cognate with Pers. vâz (in parvâz "flight"); Av. vaz- "to draw, guide; bring; possess; fly; float," vazaiti "guides, leads" (cf. Skt. vah- "to carry, drive, convey," vahati "carries," pravaha- "bearing along, carrying," pravāha- "running water, stream, river;" O.E. wegan "to carry;" O.N. vegr; O.H.G. weg "way," wegan "to move," wagan "cart;" M.Du. wagen "wagon;" PIE base *wegh- "to drive"). Bordâr "carrier," agent noun from bordan "to carry, transport" (Mid.Pers. burdan; O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive);" Skt. bharati "he carries;" Gk. pherein "to carry;" L. ferre "to carry;" PIE base *bher- "to carry"). |
vector analysis ânâlas-e bordâri Fr.: analyse vectorielle The study of → vectors and → vector spaces. |
vector angular velocity bordâr-e tondâ-ye zâviye-yi Fr.: vecteur de vitesse angulaire Of a rotating body, a vector of magnitude ω (→ angular velocity) pointing in the direction of advance of a right-hand screw which is turned in the direction of rotation. |
vector boson boson-e bordâri Fr.: boson vectoriel In nuclear physics, a → boson with the spin quantum number equal to 1. |
vector calculus afmârik-e bordâri Fr.: calcul vectoriel The study of vector functions between vector spaces by means of → differential and integral calculus. |
vector density cagâli-ye bordâr Fr.: densité de vecteur A → tensor density of → order 1. |
vector field meydân-e bordâri (#) Fr.: champ vectoriel A vector each of whose → components is a → scalar field. For example, the → gradient of the scalar field F, expressed by: ∇F = (∂F/∂x)i + (∂F/∂y)j + (∂F/∂z)k. |
vector function karyâ-ye bordâri Fr.: fonction vectorielle A function whose value at each point is n-dimensional, as compared to a scalar function, whose value is one-dimensional. |
vector meson mesoon-e bordâri Fr.: meson vectoriel Any particle of unit spin, such as the W boson, the photon, or the rho meson. |
vector perturbation partureš-e bordâri Fr.: perturbation vectorielle The perturbation in the → primordial Universe plasma caused by → vorticity. These perturbations cause → Doppler shifts that result in → quadrupole anisotropy. → vector; → perturbation. |
vector product farâvard-e bordâri Fr.: produit vectoriel Of two vectors, a vector whose direction is perpendicular to the plane containing the two initial vectors and whose magnitude is the product of the magnitudes of these vectors and the sine of the angle between them: A x B = C, C = |AB sin α|. The direction of C is given by the → right-hand screw rule. Same as → cross product. See also → scalar product. |
vector space fazâ-ye bordâri (#) Fr.: espace vectoriel A system of mathematical objects consisting of a set of (muultidimensional) vectors associated with a set of (one-dimensional) scalars, such that vectors can be added together and vectors can be multiplied by scalars while preserving the ordinary arithmetic properties (associativity, commutativity, distributivity, and so forth). |
Vega (α Lyr) Vâqe', Nasr-e Vaqe' (#) Fr.: Véga The brightest star in the constellation → Lyra and the 5th brightest star in the sky. It is an A type → main sequence star of visual magnitude 0.03. Vega is also one of the closer stars to the Earth, lying just 25.0 light-years away. Vega's axis of rotation is nearly pointing at the Earth, therefore it is viewed pole-on. Fast rotation has flattened Vega at its poles, turning it from a sphere into an oblate spheroid. The polar diameter of Vega is 2.26 times that of the Sun, and its equatorial diameter 2.75 solar. The poles are therefore hotter (10,150 K) than the equator (7,950 K). Vega, from Ar. al-Waqi' contraction of
an-Nasr al-Waqi' ( |
vegetable 1) sabzijât; 2) giyâhi Fr.: légume; 1) Any of various herbaceous plants having parts that are used as food,
such as peas, beans, cabbage, potatoes, cauliflower, and onions. 1) Sabzijât "class or category of greens," from sabzi,
→ green, + -jât a suffix denoting class,
group, or division of things. |
vegetal giyâhi (#) Fr.: végétal Of, relating to, or characteristic of plants. |
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