Physical Quantity

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Physical Quantity


an attribute that, in a qualitative respect, is a universal characteristic of many physical objects—that is, of physical systems, states of such systems, and processes occurring in such systems—but, in a quantitative respect, is independent for every object. Length, mass, and electrical resistance are examples of physical quantities that characterize the properties of objects; pressure, temperature, and magnetic induction are some of the physical quantities that characterize the state of a system; velocity and power are two of the physical quantities that characterize processes.

Various measurement methods are used for the quantitative evaluation of a physical quantity, that is, for determining the value of a physical quantity as a certain number of the units adopted for the quantity. Letter symbols are assigned to the physical quantities used in the equations of physics that express the relationships between the quantities in physical objects.

The term “physical quantity” is used not only in physics but also in other sciences, such as chemistry and biology, when a quantitative comparison of the properties of objects under study is performed by physical methods (seeMETROLOGY and DIMENSIONS).

References in periodicals archive ?
Tenders are invited for Physical Quantity Measurement System On Proprietary Basis.
The phase characteristics of the wave help monitor the change in velocity, which can be further mapped to the physical quantity being measured.
That main argument, on Friedman's view, is designed to explain precisely how each of the basic concepts of Newtonian mechanics is to be grasped as a physical quantity, and thus properly subjected to the mathematical treatment Newton gives it.
Exergy is a physical quantity defined as the maximum shaft work that can be done by the composite of a given system and a specified reference environment.
When considering light as a physical quantity, "optical radiation" has greater specificity.
However, as the velocity and deformation gradient fields form a single physical quantity, we find instructive to show that the direct definition of internal energy can be introduced at the end and that the total energy filtered through Liu's procedure can give the same results when specified to local constitutive relations.
Newton's second law has been chosen because it involves spacetime coordinates and mass and no other physical quantity or constant.
In any experiment, measuring one physical quantity with increasing precision leads to increased fuzziness in a related quantity.
A similar situation in which a physical quantity is not invariant with respect to gauge transformations of the classical electromagnetic potentials emerges in the case of a pointwise charged particle acted on by electromagnetic fields.
With the availability of ultraprecise mass spectrometrical biomolecular data, the accurate mass is said to be becoming a physical quantity of high interest in bioanalytical methodology.
This edition addresses the various applications that may be needed with reference to the practical techniques that are available for the instrumentation or measurement of a specific physical quantity or quality.
This paper is limited to a simple CIPM key comparison where the common measurand is a physical quantity of stable value during the comparison.