General introduction
Definition :
Physics describes matter and space, their properties and behaviors. The goal of physics study is to explain observed phenomena by giving care to the measurement concept called physical quantity, it is an observable property, either directly or with the help of a measuring instrument. When their measurement is expressed by a single number, it is referred to as a scalar quantity. It represents a vector quantity when a set of multiple numbers is needed. To perform quantities, they must be compared to a dimension of same nature, chosen as a unit. A physical quantity is any physical property that can be quantified and measured, under specific conditions, takes on a defined numerical value that can vary (increase or decrease). The set of units is grouped into a coherent and universal system of units called the international System (SI). Therefore, any physical quantity can be expressed based on these fundamental (base) units.