# weight

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## weight

weight, measure of the force of gravity on a body (see gravitation). Since the weights of different bodies at the same location are proportional to their masses, weight is often used as a measure of mass. However, the two are not the same; mass is a measure of the amount of matter present in a body and thus has the same value at different locations, and weight varies depending upon the location of the body in the earth's gravitational field (or the gravitational field of some other astronomical body). A given body will have the same mass on the earth and on the moon, but its weight on the moon will be only about 16% of the weight as measured on the earth. The distinction between weight and mass is further confused by the use of the same units to measure both—the pound, the gram, or the kilogram. One pound of weight, or force, is the force necessary at a given location to accelerate a one-pound mass at a rate equal to the acceleration of gravity at that location (about 32 ft per sec per sec). Similar relationships hold between the gram of force and the gram of mass and between the kilogram of force and the kilogram of mass.

## Weight

The gravitational weight of a body is the force with which the Earth attracts the body. By extension, the term is also used for the attraction of the Sun or a planet on a nearby body. This force is proportional to the body's mass and depends on the location. Because the distance from the surface to the center of the Earth decreases at higher latitudes, and because the centrifugal force of the Earth's rotation is greatest at the Equator, the observed weight of a body is smallest at the Equator and largest at the poles. The difference is sizable, about 1 part in 300. At a given location, the weight of a body is highest at the surface of the Earth. Weight is measured by several procedures. See Mass

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

## weight

The force experienced by a body on the surface of a planet, natural satellite, etc., that results from the gravitational force (directed towards the center of the planet, satellite, etc.) acting on the body. A body of mass m has a weight mg , where g is the acceleration of gravity.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Weight

the force with which a body at rest in a gravitational field acts on a suspension or horizontal support that obstructs the body’s free fall. The weight of a body P is numerically equal to the gravitational force acting upon it—that is, P = mg, where m is the mass of the body and g is the acceleration of free fall (or the acceleration of gravity). Since the mass of a body is a constant quantity (under ordinary conditions), but the value g changes on earth with latitude and altitude above sea level, the weight of a body changes correspondingly. At the same time the value g, as well as the weight, depends on the acceleration caused by the rotation of the earth around its axis; for this reason, the weight of a body at the equator is 1/288 less than at the poles.

Within a small field near the earth’s surface the value g may be considered constant and the weight of a body may be considered proportional to its mass. This assumption is used for measuring the mass of bodies by weighing them on beam balances; here the value g for the weighed body and the balance weight are considered identical. Spring balances measure the weight of a body; to determine mass when using them, it is necessary to know in addition the value of g at the point of weighing. Weight and mass are different physical quantities that cannot be considered identical; they are measured in different units—weight in units of force (newtons, kilograms-force, tons-force, and others); and mass in units of mass (kilograms, grams, tons, and so on).

A body immersed in a liquid or gas medium is acted upon, in addition to the force of gravity, by Archimedes’ force, which is equal to the weight of the displaced volume of the medium. For this reason, for example, a spring balance will show a lesser weight in an air medium than in a vacuum; for beam balances the differences in indications will depend on the ratio of the density of the balance weight to that of the weighed body.

A body at rest in an elevator that is moving vertically with an acceleration w will act on the floor of the elevator with a force F = m(g ± w) (plus sign when moving upward, minus sign downward), which is equivalent to an increase (overload) or decrease in weight. During free fall of the elevator (w = g), weightlessness occurs; such a state occurs for any body that is moving freely and progressively in a gravitational field (a rocket, satellite, and so on).

S. M. TARG

## What does it mean when you dream about a weight?

Being weighed down in a dream may indicate that the dreamer is waiting for someone or something to change before they can feel unburdened in their life. Lightness, alternatively, often represents lighter, or more positive, emotions.

## weight

[wāt]
(mathematics)
The unique nonnegative integer assigned to an edge or arc in a network or directed network.
The sum of the weights (first definition) of all the arcs in an s-t cut.
The nonnegative integer assigned to a vertex in a generalized s-t network.
The sum of the weights of all the arcs and vertices in a generalized s-t cut.
(mechanics)
The gravitational force with which the earth attracts a body.
By extension, the gravitational force with which a star, planet, or satellite attracts a nearby body.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## weight

1. Physics the vertical force experienced by a mass as a result of gravitation. It equals the mass of the body multiplied by the acceleration of free fall. Its units are units of force (such as newtons or poundals) but is often given as a mass unit (kilogram or pound).
2. a system of units used to express the weight of a substance
3. a unit used to measure weight
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The mean gestational age in weeks for LBW, VLBW and ELBW groups were 36.06, 32.76, and 29.5, respectively.
Our clinicians found that improved outcomes in ELBW infants can be achieved by changing the culture of the practice.
A similar study in New Zealand found that 20-40% of the children with ELBW exhibited high levels of behavioral problems, cognitive impairment and poor school achievement as opposed to 7-20% of a control cohort.
The height and weight of the ELBW study participants at adolescence was statistically similar to the term children (160 cm and 55 kg), but 73% of the ELBW adolescents had vision problems, compared with 38% of the term adolescents, Ms.
Repetitive pain and environmental stress in ELBW infants (<1,000 g) is associated with cognitive defects, learning disorders, poor motor performance, attention deficits, psychosocial problems, and inability to adapt and cope in new situations and social situations (Anand, Grunau, & Oberlander, 1997; Grunau, 2000).
At both age 8 and 16, scores on the Wechsler Intelligence Scale for Children-Revised were 13-18 points lower in the ELBW group than in the control group.
[11,12] Improved survival of VLBW and ELBW infants has resulted in increased morbidity, including necrotising enterocolitis (NEC), intraventricular haemorrhage (IVH), periventricular leucomalacia (PVL), patent ductus arteriosus (PDA), retinopathy of prematurity (ROP) and sepsis.
On the basis of the birth weight, 17 newborns (44,7%) are VLBW with BW <1500 grams, 14 newborns (36,8%) are ELBW with birth weight <1000 gr, and 5 of them (13,1%) weigh less than 500 grams.
Five studies documenting the mortality of extremely-low-birth-weight (ELBW) neonates, weighing <1 000 g, were combined (N=13 093) and showed an 80% increased risk of mortality in outborns.
Extremely low birth weight (ELBW) neonates were at highest risk to develop hypoglycemia (82.35%).
investigated the cardiac outcome of young adults born with extremely low birth weight (ELBW) .

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