In thermodynamics and materials science, the physical properties of substances are often described as intensive or extensive, a classification that relates to the dependency of the properties upon the size or extent of the system or object in question.
The distinction is based on the concept that smaller, non-interacting identical subdivisions of the system may be identified so that the property of interest does or does not change when the system is divided, or combined.
A physical property is any property that is measurable whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its transformations or evolutions between its momentary states. Physical properties are often referred to as observables. They are not modal properties.
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.
Most local governments in the United States impose a property tax as a principal source of revenue. This tax may be imposed on real estate or personal property. The tax is nearly always computed as the fair market value of the property times an assessment ratio times a tax rate. Values are determined by local officials, and may be disputed by property owners. A very important advantage of the property tax over the sales tax or income tax a tax is that the revenue always equals the tax levy, unlike the other taxes, which can result in shortfalls producing budget deficits. The property tax always produces the required revenue for municipalities' tax levies.
The tax is administered at the local government level. Many states impose limits on how local jurisdictions may tax property. Since many properties are subject to tax by more than one local jurisdiction, some states provide a method by which values are made uniform among such jurisdictions.
A physical quantity (or "physical magnitude") is a physical property of a phenomenon, body, or substance, that can be quantified by measurement.