An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 5 Search : three
restricted three-body problem
  پراسه‌ی ِ سه‌جسم ِ فروداریده   
parâse-ye seh jesm-e forudâridé

Fr.: problème restreint à trois corps   

A special case of the → three-body problem in which the → mass of one of the bodies is negligible compared to that of the two others. If the relative motion of the two massive components is a circle, the situation is referred to as the → circular restricted three-body problem. An example would be a space probe moving in the → gravitational fields of the → Earth and the → Moon, which revolve very nearly in circles about their common → center of mass.

restrict; → three; → body; → problem.

rule of three
  رزن ِ سه   
razan-e sé

Fr.: règle de trois   

Te method of finding the fourth term in a proportion when three terms are given.

rule; → three.

three
  سه   
sé (#)

Fr.: trois   

A cardinal number, 2 plus 1.

M.E.; O.E. threo, thrib, feminin and neuter of thri(e); cf. O.Fris. thre, M.Du., Du. drie, O.H.G. dri, Ger. drei, Dan. tre), cognate with Pers. , as below.

, from Mid.Pers. ; Av. θrayô, θrayas, tisrô, θri; cf. Skt. tráya, tri, trini; Gk. treis, L. tres, Lith. trys, O.C.S. trye, Ir., Welsh tri, O.E. threo, as above; PIE base *trei-.

three-body problem
  پر‌آسه‌ی ِ سه‌جسم   
parâse-ye sé jesm

Fr.: problème à trois corps   

The mathematical problem of studying the positions and velocities of three mutually attracting bodies (such as the Sun, Earth and Moon) and the stability of their motion. This problem is surprisingly difficult to solve, even in the simple case, called → restricted three-body problem, where one of the masses is taken to be negligibly small so that the problem simplifies to finding the behavior of the mass-less body in the combined gravitational field of the other two. See also → two-body problem, → n-body problem.

three; → body; → problem.

three-dimensional flow
  تچان ِ سه-وامونی   
tacân-e sé-vâmuni

Fr.: écoulement tri-dimensionnel   

A flow whose parameters (velocity, pressure, and so on) vary in all three coordinate directions. Considerable simplification in analysis may often be achieved, however, by selecting the coordinate directions so that appreciable variation of the parameters occurs in only two directions, or even only one (B. Massey, Mechanics of Fluids, Taylor & Francis, 2006).

three; → dimensional; → flow.