Editing Physical property (section)

{{Short description|Attribute of a physical system or body or non-chemical property of a material}}
{{For|the legal concept|Tangible property| intangible property}}
{{more citations needed|date=March 2017}}

A '''physical property''' is any [[Property (philosophy)|property]] of a [[physical system]] that is [[Measurement|measurable]].<ref>{{Cite book|url=https://books.google.com/books?id=FmptDQAAQBAJ&q=A+physical+property+is+any+property+that+is+measurable%2C+whose+value+describes+a+state+of+a+physical+system.+-cram101+-cti&pg=PA502|title=Theory Of Knowledge: Structures And Processes|last=Mark|first=Burgin|date=2016-10-27|publisher=World Scientific|isbn=9789814522694|language=en|url-status=live|archiveurl=https://web.archive.org/web/20171225222650/https://books.google.com/books?id=FmptDQAAQBAJ&pg=PA502&dq=A+physical+property+is+any+property+that+is+measurable,+whose+value+describes+a+state+of+a+physical+system.+-cram101+-cti&hl=en&sa=X&ved=0ahUKEwilhY3SmabYAhUKs1QKHUbtD_4Q6AEIKTAA#v=onepage&q=A%20physical%20property%20is%20any%20property%20that%20is%20measurable,%20whose%20value%20describes%20a%20state%20of%20a%20physical%20system.%20-cram101%20-cti&f=false|archivedate=2017-12-25}}</ref> The changes in the physical properties of a system can be used to describe its changes between momentary states. A [[Quantity|quantifiable]] physical property is called ''[[physical quantity]]''. [[Measurement|Measurable]] physical quantities are often referred to as ''[[observable]]s''. 
Some physical properties are [[qualitative property|qualitative]], such as [[shininess]], [[brittleness]], etc.; some general qualitative properties admit more specific related quantitative properties, such as in [[Opacity_(optics)#Quantitative_definition|opacity]], [[Hardness#Measures|hardness]], [[Ductility#Quantification|ductility]], [[viscosity#Definitions|viscosity]], etc.

Physical properties are often characterized as [[intensive and extensive properties]]. An intensive property does not depend on the size or extent of the system, nor on the amount of matter in the object, while an extensive property shows an additive relationship. These 
classifications are in general only valid in cases when smaller subdivisions of the sample do not interact in some physical or chemical process when combined.

Properties may also be classified with respect to the directionality of their nature. For example, [[isotropy|isotropic]] properties do not change with the direction of observation, and [[anisotropy|anisotropic]] properties do have spatial variance.

It may be difficult to determine whether a given property is a material property or not.  [[Color]], for example, can be seen and measured; however, what one perceives as color is really an interpretation of the reflective properties of a surface and the light used to illuminate it. In this sense, many ostensibly physical properties are called [[supervenience|supervenient]]. A supervenient property is one which is actual, but is secondary to some underlying reality. This is similar to the way in which objects are supervenient on atomic structure. A cup might have the physical properties of mass, shape, color, temperature, etc., but these properties are supervenient on the underlying atomic structure, which may in turn be supervenient on an underlying quantum structure.

Physical properties are contrasted with [[Chemical property|chemical properties]] which determine the way a material behaves in a [[chemical reaction]].