jonbeš-e šetâbdâr (#)
Fr.: mouvement accéléré
Jonbeš, → motion; šetâbdâr "accelerated," from šetâb→ accelerate + dâr "having, possessor" (from dâštan "to have, to possess," Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maitain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE *dher- "to hold, support").
annual apparent motion
jonbeš-e sâlâne-ye padidâr
Fr.: mouvement annuel apparent
Fr.: mouvement annuel
The annual apparent motion of the → Sun in the sky with respect to → fixed stars along the path called → ecliptic. The apparent annual motion is due to the → Earth's → revolution about the Sun. In the course of this motion, the Sun appears to shifts about 1° eastward per day.
Fr.: mouvement apsidial
→ Rotation of the → line of apsides in the plane of the orbit in the same direction as the → revolution of the → secondary body. The major axis of the Earth's orbit rotates by 11.6 arcseconds per year.
Fr.: mouvement brownien
The continuous random motion of solid microscopic particles immersed in a fluid, which is due to bombardment by the atoms and molecules of the medium. It is named after the botanist Robert Brown, who in 1827 first noticed that pollen seeds suspended in water moved in an irregular motion. While there were suspicions that the motion was caused by the collision of atoms against the particles, the first quantitative explanation of the phenomenon, based on the kinetic theory of gases, was forwarded by A. Einstein in 1905. When Einstein's paper appeared, the notion of atoms and molecules was still a subject of heated scientific debate. Ernst Mach and the physical chemist Wilhelm Ostwald were among those who chose to deny their existence.
Named after Robert Brown (1773-1858), a Scottish botanist, who first in 1827 noticed the erratic motion of pollen grains suspended in water. → motion.
jonbeš-e dâyere-yi, ~ parhuni
Fr.: mouvement circulaire
Motion in which an object moves in a circle at a constant speed. The velocity, however, changes not because the magnitude of the velocity changes, but because its direction changes. The changing velocity creates an acceleration, called → centripetal acceleration. This acceleration results from the → centripetal force.
Fr.: mouvement co-orbital
The motion of two or more bodies around the Sun on different orbits when it takes them the same amount of time to complete one revolution. There are three possible types of co-orbital motions of a small body associated with a planet: → tadpole orbits, → horseshoe orbits, and → quasi-satellite orbits.
constant of the motion
Fr.: constante de mouvement
1) Classical mechanics: A variable X whose total rate of change dX/dt
along the path of a → dynamical system is zero. In other words,
a function of an object's position, velocity, or both that does not change even as the
object moves. For example, the total energy of a
→ simple harmonic oscillator is a constant of the motion.
differential image motion monitor (DIMM)
pahregar-e jonbeš-e degarsâneyi-ye vine, ~ ~ ~ tasvir
Fr.: moniteur de mouvements d'images différentiels, moniteur seeing
A device that is commonly used to measure the → seeing at optical astronomical sites. The DIMM delivers an estimate of the → Fried parameter based on measuring the variance of the differential image motion in two small apertures, usually cut out in a single larger telescope pupil by a mask. The DIMM concept was introduced by Stock & Keller (1960, in Stars and Stellar Systems, Vol. 1, ed. G. P. Kuiper & B. M. Middlehurst, p. 138), whereas its modern implementation was first described by Sarazin & Roddier (1990, A&A 227, 294).
jonb eš-e farârow, ~ sarrâst
Fr.: mouvement direct
The motion of a solar system body from West to East across the sky against the background stars. It is the "normal" direction of motion within the solar system. For rotating or orbiting solar system objects it is anti-clockwise as seen from above the solar system in the direction of the North Pole. The same as → prograde motion. See also → retrograde motion.
Fr.: mouvement diurne
The daily apparent motion of all celestial objects, due to Earth's rotation.
equation of motion
Fr.: équation de mouvement
1) Any equation that describes the motion of objects, i.e., variation of
velocity, distance covered, acceleration, etc., as a function of time;
e.g., V = V0 +
at, S = Vt + (1/2)at2.
jonbeš-e hamâhang (#)
Fr.: mouvement harmonique
A motion that repeats itself in equal intervals of time (also called periodic motion).
jonbeš-e laxtinâk, ~ laxtimand
Fr.: mouvement inertiel
Motion free of any force, with constant velocity.
mean daily motion
jenbeš-e ruzâne-ye miyângin (#)
Fr.: mouvement diurne moyen
The average movement of a body along its orbit in one day, usually expressed in degrees.
jonbeš-e miyângin (#)
Fr.: mouvement moyen
The average angular velocity of a satellite in an elliptical orbit.
The action or process of moving or of changing place or position; movement.
Verbal noun of → move.
Newton's first law of motion
naxostin qânun-e Newtoni-ye jonbeš (#)
Fr.: première loi newtonienne de mouvement
A body continues in its state of constant velocity (which may be zero) unless it is acted upon by an external force.
Newton's laws of motion
qânunhâ-ye jonbeš-e Newton
Fr.: lois de mouvement de Newton
Newton's second law of motion
dovomin qânun-e Newtoni-ye jonbeš (#)
Fr.: seconde loi newtonienne de mouvement
For an unbalanced force acting on a body, the acceleration produced is proportional to the force impressed; the constant of proportionality is the inertial mass of the body.