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**In science and engineering, the weight of an object is usually taken to be the force on the object due to gravity. **

Engineering is the application of mathematics, empirical evidence and scientific, economic, social, and practical knowledge in order to invent, innovate, design, build, maintain, research, and improve structures, machines, tools, systems, components, materials, processes and organizations.

In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.

Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward one another, including planets, stars and galaxies.

Shawn Mendes - The Weight by ShawnMendesVEVO

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**Weight is a vector whose magnitude, often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus: W = mg. **

The Band, The Weight by Tskeshi Kawaguchi

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**The unit of measurement for weight is that of force, which in the International System of Units is the newton. **

A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity.

The International System of Units is the modern form of the metric system, and is the most widely used system of measurement.

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**For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, and about one-sixth as much on the Moon. **

The kilogram or kilogramme is the base unit of mass in the International System of Units, and is defined as being equal to the mass of the International Prototype of the Kilogram, a cylinder of platinum-iridium alloy stored by the International Bureau of Weights and Measures at Saint-Cloud, France.

The Moon is an astronomical body that orbits planet Earth, being Earth's only permanent natural satellite.

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**In this sense of weight, a body can be weightless only if it is distant from any other mass. Although weight and mass are scientifically distinct quantities, the terms are often confused with each other in everyday use.
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**There is also a rival tradition within Newtonian physics and engineering which sees weight as that which is measured when one uses scales. **

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**There the weight is a measure of the magnitude of the reaction force exerted on a body. **

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**Typically, in measuring an object's weight, the object is placed on scales at rest with respect to the earth, but the definition can be extended to other states of motion. **

The ear is the organ of hearing and, in mammals, balance.

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**Thus, in a state of free fall, the weight would be zero. **

In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it.

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**In this second sense of weight, terrestrial objects can be weightless. **

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**Ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, is weightless.
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Sir Isaac Newton FRS was an English physicist and mathematician who is widely recognised as one of the most influential scientists of all time and a key figure in the scientific revolution.

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**Further complications in elucidating the various concepts of weight have to do with the theory of relativity according to which gravity is modelled as a consequence of the curvature of spacetime. **

The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity.

In physics, spacetime is any mathematical model that combines space and time into a single interwoven continuum.

In mathematics, curvature is any of a number of loosely related concepts in different areas of geometry.

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**In the teaching community, a considerable debate has existed for over half a century on how to define weight for their students. **

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**The current situation is that a multiple set of concepts co-exist and find use in their various contexts.**