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mean free path puyeš-e âzâd-e miyângin (#) Fr.: libre parcours moyen The mean distance which a particle moves between two successive collisions with other particles of the medium. Mean free path is inversely proportional to the number of particles per cm^{3} (n), and the collision → cross section (σ). In the case of a gas with molecules having a diameter of d, the cross section is equal to the area of a circle of radius d, i.e. σ = πd^{2}, and the mean free path is given by: l = 1/(nσ). Taking into account the relative velocity distribution of the colliding molecules, l = 1/(√2 . nσ). For a gas at one atmosphere pressure and room temperature, the average distance between molecules is roughly 3.5 × 10^{-7} cm, that is some 35 times the diameter of a molecule. Taking the gas density n = 2.4 × 10^{14} molecules cm^{-3}, and a typical diameter d = 2 × 10^{-8} cm for a molecule, the mean free path is 3.3 × 10^{-5} cm. This means that the average distance between collisions is about 95 times the average distance between molecules. Puyeš, verbal noun of puyidan "to run, trot; wander," from Mid.Pers. pôy-, pwd- "to run;" cf. Gk. speudein "to hasten;" Lith. spudinti; âzâd, → free; miyângin, → mean. |
mean life zist-e miyângin Fr.: vie moyenne The average amount of time an unstable radioisotope exists before it decays, It is equal to 1.44 times the half-life. |
mean molecular weight vazn-e molekuli-ye miyângin (#) Fr.: poids moléculaire moyen The total atomic or molecular weight divided by the total number of particles. For instance, the mean molecular weight of a plasma of pure ionized ^{4}He would be 4 (the atomic mass number) divided by 3, the total number of particles (1 nucleus plus 2 electrons), i.e. 4/3. |
mean moon mâh-e miyângin (#) Fr.: lune moyenne A fictitious Moon that has the same average motion as the true Moon but that is not subject to any gravitational perturbations by other bodies. |
mean motion jonbeš-e miyângin (#) Fr.: mouvement moyen The average angular velocity of a satellite in an elliptical orbit. |
mean parallax didgašt-e miyângin Fr.: parallaxe moyenne The parallax, derived by means of statistical studies of brightness and motions, for a large group of stars whose individual parallaxes cannot be measured. |
mean place jâ-ye miyângin Fr.: position moyenne An object's celestial position as determined for a given mean equator and equinox. → mean position. |
mean pole qotb-e miyângin Fr.: pôle moyen The direction of the Earth's axis at a particular epoch if the nutation is ignored. |
mean position neheš-e miyângin Fr.: position moyenne Same as → mean place. |
mean profile farâpâl-e miyângin Fr.: profil moyen The shape of a pulsar's pulse as determined by averaging several pulses. |
mean sidereal day ruz-e axtari-ye miyângin Fr.: jour sidéral moyen The average time interval between two successive → upper transits of the → mean equinox. |
mean sidereal time zamân-e axtari-ye miyângin (#) Fr.: temps sidéral moyen The hour angle of the mean equinox for a given observer. |
mean solar day ruz-e xoršidi-ye miyângin (#) Fr.: jour solaire moyen The average length of the apparent solar day. In other words, the interval between successive transits of the mean Sun for a given observer. |
mean solar time zamân-e xoršidi-ye miyângin (#) Fr.: temps solaire moyen The time since the mean Sun crossed the meridian with 12 hours added to make the day begin at midnight. |
mean spectrum binâb-e miyângin Fr.: spectre moyen A plot of the mass-to-charge ratio of elementary particles, sorted by their isotopic mass. |
mean Sun xoršid-e miyângin (#) Fr.: Soleil moyen A hypothetical Sun that moves along the ecliptic at a uniform rate equal to the average motion of the real Sun. |
mean term tarm-e miyâni Fr.: terme moyen In → syllogism, the term which is common to both → premises and is excluded from the → conclusion. |
mean value theorem farbin-e arzeš-e miyângin Fr.: théorème des accroissements finis 1) If f(x) is a continuous function on the interval from a to b, then: |
meaning cemâr (#) Fr.: sens, signification The sense or significance of a word, sentence, symbol, etc. The study dealing with meanings is called → semantics. See also → semiotics. M.E., from mean; O.E. mænan "to mean, intend, signify" (cf. O.Fris. mena "to signify," O.S. menian "to intend, signify," M.Du. menen, Du. meenen, Ger. meinen "think, suppose"), related to Pers. maneš "disposition, temperament," mênidan "to think, consider," → idea; + → -ing. Cemâr, from cem or cim "meaning, signification;" Mid.Pers. cim "meaning, reason, cause;" ultimately from Proto-Ir. *cahmāt "wherefore?" cf. Skt. kasmāt "why, where from? whence?," kim "what? how? why?" + âr short form of âvar present stem of âvardan "to cause or produce; to bring," → production, as in bonâr, → cause, used also as a nuance suffix; see also the verb → mean. |
measure 1) (n.) andâzé (#); 2) (v.) andâzé gereftan (#) Fr.: 1) mesure; 2) mesurer 1) A unit or standard of → measurement;
the act or process of ascertaining the extent, dimensions, or quantity of
something; measurement. From O.Fr. mesurer, from L.L. mensurare "to measure," from L. mensura "a measuring, a thing to measure by," from mensus, p.p. of metiri "to measure," → meter. 1) Andâzé "measure," from Mid.Pers. andâzag, handâcak "measure,"
handâxtan, handâz- "to measure,"
Manichean Mid.Pers. hnds- "to measure," Proto-Iranian *hamdas-, from
ham-, → com-, + *das- "to heap, amass;" cf.
Ossetic dasun/dast "to heap up;"
Arm. loanword dasel "to arrange (a crowd, people)," das "order, arrangement." |
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