Physics

Definition

The weight of a naked body or forces Pesanteur is the force exerted on a body (of Masse m) motionless in the terrestrial reference frame (i.e., bound to the solid object Ground in rotation), by the gravitation of the other masses and the inertial forces (due to the fact that the terrestrial reference frame is not a Référentiel galiléen). Whatever the body, the report/ratio of the weight (P) to its mass (m) identical and is noted G: P = m G . As opposed to what thinks people, the weight is the force by which attraction attracts an object and not the number of kilos, the number of kilos of a person is expressed in mass and not in weight.

So all the bodies fall, in the vacuum, according to same acceleration has = G (law of Galileo (1564-1642)). For more details, to see freefall.

The mass m being expressed in kilogram (kg), the weight is a force and thus has like unit the newton (symbol NR), and acceleration G will be indifferently expressed in N/kg or m/s ².

The not-distinction between mass and weight lasts to the XIXe century, and perdure in the current language. For example: “the body mass of a person” is usually called her “weight”. It results a teaching difficulty from it, at the moment when this distinction is taught. The adoption of the International System (S.I.) made it possible thanks to the suppression of the unit kilogram-weight to partially solve this difficulty.

The acceleration of gravity G is the object of study of the Gravimétrie. It varies in any point of the Earth, primarily decreasing by the pole (9.83) at the equator (9.78). In France, one conventionally takes the value of G in Paris, that is to say approximately: G = 9.81 N/kg.

The concept of gravity spreads with other celestial bodies, in particular the Moon where gravity is approximately six times less than on Earth.

The concepts of apparent weight and weightlessness are related to the change of definition which had with the change of reference frame.

How to find it

Knowing that the ray (R) of the Earth is equal to 6380 km and its mass (M) with 5,98*10^ {24} kg, one can determine the value of the constant G which is exerted on an unspecified object of mass m :

m \ frac {GM} {R^2} \ simeq m*9,81

It is pointed out that G is the universal constant of gravitation.

Mathematics

The weights , in Mathematical, is also the value which one allots to a symbol according to his place in a number.

example: 101 = 100 + 1. The first “1” has a weight of 100 (because in third position on the basis of the line), while the second “1” with a weight unit (first position on the basis of the line). The association of both form value 101.

The weight is also the affected coefficient or weighting at a point in a barycentre (in reference to physics where the barycentre calls upon the masses)

example: if G is the Barycentre system {(has, 1) (B, 3)} , it is said that has is affected weight 1 and B of weights 3

Like energy source

The descent of weight makes it possible to actuate a mechanism such as an automat or a clock. This type of dispostif was replaced by a driving Ressort.

Data processing

In data processing, the terms relating to the weight of a solid are also sometimes employed by analogy with the Taille of the files (weight of a file, heavy file, light file), and the Consommation of the resources of a process (light Processus).

See too

Simple: Weight Zh-min-nan: Tāng-liōng

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