Newton's third law of motion
sevomin qânun-e Newtoni-ye jonbeš (#)
Fr.: troisième loi newtonienne de mouvement
In a system where no external forces are present, every action force is always opposed by an equal and opposite reaction.
Fr.: mouvement parallactique
The proper motion of a star due to the effect of the Sun's motion relative to the → local standard of rest.
Fr.: mouvement particulier
1) The true motion of a star with respect to the Local Standard
of Rest. → proper motion.
Fr.: mouvement périodique
Any motion that recurs in identical forms at equal intervals of time.
Fr.: mouvement perpétuel
The motion of a hypothetical machine which, once set in motion, will go on for ever without any losses due to → friction or other forms of → dissipation of energy and without receiving any external energy.
Fr.: mouvement à la Poinsot
The motion of a torque free rotating rigid body in space, in general whose angular velocity vector precesses regularly about the constant angular momentum factor.
After Louis Poinsot (1777-1859), French physicist and mathematician. He was the inventor of geometrical mechanics, showing how a system of forces acting on a rigid body could be resolved into a single force and a couple.
Fr.: mouvement du pôle
The irregularly varying motion of the Earth's pole of rotation with respect to the Earth's crust.
Fr.: mouvement prograde
A rotational or orbital movement that is the same as most bodies within a celestial system. In the solar system, the apparent eastward motion of a celestial body on the celestial sphere. Opposed to → retrograde motion. Same as → direct motion.
1) The act of promoting someone to a higher job, grade, or rank, or the fact
of being so promoted.
Verbal noun of → promote.
Fr.: mouvement propre
The apparent motion of a star across the sky (not including a star's parallax), arising from the star's velocity through space with respect to the Sun. Proper motion is usually tabulated in star catalogs as changes in right ascension and declination per year or century. See also: → proper motion distance.
proper motion distance
durâ-ye jonbeš-e saré
Fr.: distance mouvement propre
The distance derived from the → proper motion of an object. If an object has a known → transverse velocity u, and has an observed angular motion of dθ/dt, then the proper motion distance is defined as: d = u/(dθ/dt).
Fr.: mouvement quasipériodique
In a dynamical system, a form of motion that is regular but never exactly repeating. Quasiperiodic motion appears when the system contains two or more incommensurate frequencies.
Fr.: mouvement radial
A motion away from or toward a central point or axis.
random thermal motion
jonbeš-e garmâyi-ye kâturé
Fr.: mouvement thermique aléatoire
Fr.: mouvement rétrograde
The orbital motion or rotation of a solar system body in a clockwise direction (East to West) when viewed from the north pole of the ecliptic. It is a motion opposed to the → direct motion of the great majority of solar system bodies.
Fr.: mouvement de rotation
Of a → rigid body, a motion in which there are always two points of the body which remain motionless.
simple harmonic motion
jonbeš-e hamâhang-e sâdé
Fr.: mouvement harmonique
The motion of a body subjected to a restraining force which is directly proportional to the displacement from a fixed point in the line of motion. The equation of simple harmonic motion is given by x = A sin(ωt + θ0), where x is the body's displacement from equilibrium position, A is the → amplitude, or the magnitude of harmonic oscillations, ω is the → angular frequency, t is the time elapsed, and θ0 is the → initial phase angle.
Fr.: mouvement spatial
The velocity and direction of motion of a star or celestial object with respect to the Local Standard of Rest. Same as → peculiar velocity.
Fr.: mouvement superluminal
Apparent proper motion exceeding the velocity of light seen toward certain astronomical objects, such as the jets of radio galaxies and quasars. However, these jets are not actually moving at speeds in excess of the speed of light: the apparent superluminal motion is a projection effect caused by objects moving near the speed of light and at a small angle to the line of sight.
Fr.: mouvement tangentiel
That component of a an object's motion which is perpendicular to the observer's → line of sight.