An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -ne Nao nat nea neg nes neu New New niv noi non non nor nov nuc nul num > >>

Number of Results: 357
Newton's disk
  گرده‌ی ِ نیوتن   
gerde-ye Newton

Fr.: disque de Newton   

Newton's color wheel.

Newton; → disk.

Newton's equation
  هموگش ِ نیوتن   
hamugeš-e Newton

Fr.: équation de Newton   

In → geometric optics, an expression relating the → focal lengths of an → optical system (f and f') and the object x and image x' distances measured from the respective focal points. Thus, ff' = xx'. Same as Newton's formula.

Newton; → equation.

Newton's first law of motion
  نخستین قانون ِ نیوتنی ِ جنبش   
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; → first; → law; → motion.

Newton's law of cooling
  قانون ِ سردش ِ نیوتن   
qânun-e sardeš-e Newton

Fr.: loi de refroidissement de Newton   

An approximate empirical relation between the rate of → heat transfer to or from an object and the temperature difference between the object and its surrounding environment. When the temperature difference is not too large: dT/dt = -k(T - Ts), where T is the temperature of the object, Ts is that of its surroundings, t is time, and k is a constant, different for different bodies.

Newton; → law; → cooling.

Newton's law of gravitation
  قانون ِ گرانش ِ نیوتن   
qânun-e gerâneš-e Newton

Fr.: loi newtonienne de la gravitation   

The universal law which states that the force of attraction between any two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them: F = G (m1.m2)/r2, where G is the → gravitational constant.

Newton; → law; → gravitation.

Newton's laws of motion
  قانونهای ِ جنبش ِ نیوتون   
qânunhâ-ye jonbeš-e Newton

Fr.: lois de mouvement de Newton   

The three fundamental laws which are the basis of → Newtonian mechanics. They were stated in Newton's Principia (1687). → Newton's first law, → Newton's second law , → Newton's third law.

Newton; → law; → motion.

Newton's method
  روش ِ نیوتن   
raveš-e Newton

Fr.: méthode de Newton   

Same as the → Newton-Raphson method.

Newton; → method.

Newton's rings
  حلقه‌های ِ نیوتن   
halqehâ-ye Newton (#)

Fr.: anneaux de Newton   

Colored circular → fringes formed when light beams reflected from two polished, adjacent surfaces, placed together with a thin film of air between them, interfere. → interference.

Newton; → ring.

Newton's second law of motion
  دومین قانون ِ نیوتنی ِ جنبش   
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.

Newton; → second; → law; → motion.

Newton's shell theorem
  فربین ِ پوسته‌ی ِ نیوتن   
farbin-e puste-ye Newton

Fr.: théorème de Newton   

In classical mechanics, an analytical method applied to a material sphere to determine the gravitational field at a point outside or inside the sphere. Newton's shell theorem states that: 1) The gravitational field outside a uniform spherical shell (i.e. a hollow ball) is the same as if the entire mass of the shell is concentrated at the center of the sphere. 2) The gravitational field inside the spherical shell is zero, regardless of the location within the shell. 3) Inside a solid sphere of constant density, the gravitational force varies linearly with distance from the center, being zero at the center of mass. For the relativistic generalization of this theorem, see → Birkhoff's theorem.

Newton; → shell; → theorem.

Newton's third law of motion
  سومین قانون ِ نیوتنی ِ جنبش   
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.

Newton; → third; → law; → motion.

Newton-Leibniz formula
  دیسول ِ نیوتن-لایبنیتس   
disul-e Newton-Leibniz

Fr.: formule de Newton-Leibniz   

The formula expressing the value of a → definite integral of a given function over an interval as the difference of the values at the end points of the interval of any → antiderivative of the function: ∫f(x)dx = F(b) - F(a), summed from x = a to x = b.

Named after Isaac → Newton and Gottfried Wilhelm Leibniz (1646-1716), who both knew the rule, although it was published later; → formula.

Newton-Maxwell incompatibility
  ناسازگاری ِ نیوتن-ماکسول   
nâsâzgâri-ye Newton-Maxwell

Fr.: incompatibilité entre Newton et Maxwell   

The incompatibility between → Galilean relativity and Mawxell's theory of → electromagnetism. Maxwell demonstrated that electrical and magnetic fields propagate as waves in space. The propagation speed of these waves in a vacuum is given by the expression c = (ε00)-0.5, where ε0 is the electric → permittivity and μ0 is the magnetic → permeability, both → physical constants. Maxwell noticed that this value corresponds exactly to the → speed of light in vacuum. This implies, however, that the speed of light must also be a universal constant, just as are the electrical and the magnetic field constants! The problem is that → Maxwell's equations do not relate this velocity to an absolute background and specify no → reference frame against which it is measured. If we accept that the principle of relativity not only applies to mechanics, then it must also be true that Maxwell's equations apply in any → inertial frame, with the same values for the universal constants. Therefore, the speed of light should be independent of the movement of its source. This, however, contradicts the vector addition of velocities, which is a verified principle within → Newtonian mechanics. Einstein was bold enough to conclude that the principle of Newtonian relativity and Maxwell's theory of electromagnetism are incompatible! In other words, the → Galilean transformation and the → Newtonian relativity principle based on this transformation were wrong. There exists, therefore, a new relativity principle, → Einsteinian relativity, for both mechanics and electrodynamics that is based on the → Lorentz transformation.

Newton; → Maxwell; → incompatibility.

Newton-Raphson method
  روش ِ نیوتن-رفسون   
raveš-e Newton-Raphson

Fr.: méthode de Newton-Raphson   

A method for finding roots of a → polynomial that makes explicit use of the → derivative of the function. It uses → iteration to continually improve the accuracy of the estimated root. If f(x) has a → simple root near xn then a closer estimate to the root is xn + 1 where xn + 1 = xn - f(xn)/f'(xn). The iteration begins with an initial estimate of the root, x0, and continues to find x1, x2, . . . until a suitably accurate estimate of the position of the root is obtained. Also called → Newton's method.

Newton found the method in 1671, but it was not actually published until 1736; Joseph Raphson (1648-1715), English mathematician, independently published the method in 1690.

Newtoni (#)

Fr.: newtonien   

Of or pertaining to Sir Isaac Newton or to his theories or discoveries.

Newtonian, from → Newton + -ian a suffix forming adjectives.

Newtonian approximation
  نزدینش ِ نیوتنی   
nazdineš-e Newtoni

Fr.: approximation newtonienne   

A particular solution of the → general relativity when the → gravitational mass is small. The → space-time is then approximated to the → Minkowski's and this leads to → Newtonian mechanics.

Newtonian; → approximation.

Newtonian constant of gravitation
  پایای ِ گرانش ِ نیوتن   
pâyâ-ye gerâneš-e Newton

Fr.: constante de la gravitation newtonienne   

Same as the → gravitational constant.

Newtonian; → constant; → gravitation.

Newtonian cosmology
  کیهان‌شناسی ِ نیوتنی   
keyhânšenâsi-ye Newtoni

Fr.: cosmologie newtonienne   

The use of → Newtonian mechanics to derive homogeneous and isotropic solutions of → Einstein's field equations, which represent models of expanding Universe. The Newtonian cosmology deviates from the prediction of → general relativity in the general case of anisotropic and inhomogeneous models.

Newtonian; → cosmology.

Newtonian fluid
  شاره‌ی ِ نیوتنی   
šârre-ye Newtoni

Fr.: fluide newtonien   

Any → fluid with a constant → viscosity at a given temperature regardless of the rate of → shear.

Newtonian; → fluid.

Newtonian focus
  کانون ِ نیوتن، ~ نیوتنی   
kânun-e Newton, ~ Newtoni

Fr.: foyer de Newton   

The focus obtained by diverting the converging light beam of a reflecting telescope to the side of the tube.

Newtonian; → focus.

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