Nature of Physical Quantities

 Interactions between the physical system and the environment bring changes in the state of the former. This is established by the changes in the properties of the system known as the physical quantities. These changes are observable and can be measured. This article tries to gain further insight on this topic.

Nature of Physical Quantities:

• ·        They are terms which define the characteristics of a physical system and its environment.
• ·        Those quantities, associated with the system, are called the state variables.
• ·        The quantities which move across the system boundary are known as transfer variables.
• ·        While certain physical quantities are constants, others are variables in nature.
• ·        Technically, the properties of the system which can be measured using a measuring device are known as its physical quantities.
• ·        Most of the physical quantities are the observable characteristics of the system.
• ·        However, there are certain physical quantities which are defined strictly out of the need of scientific analysis. Ex: Reynold’s number in fluid mechanics, critical angle in optics, etc.
• ·        Mathematically, physical quantities are classified as either scalars or as vectors.
• ·        The quantities which only have a magnitude and no specific direction are known as Scalar quantities.
• ·        The quantities which have a specific magnitude in a specific direction are known as Vector quantities.
• ·        Physical quantities can have technical as well as operational definitions.

Conclusion: Proper selection of the physical quantities consistent with the objective of study is crucial to the success of a scientific analysis.