Seven basic physical quantities and units: length m, time s, mass kg, thermodynamic temperature k (Kelvin temperature), current a, light intensity cd (Candeira), and quantity of matter mol.

There are many formulas in physics, all of which are expressed by physical quantities, that is, physical symbols. In a broad sense, algebra in junior high school mathematics should also be regarded as a physical quantity, paving the way for physical formulas. Mole is obviously a unit, because there must be data in front, the amount of matter = 123 mole, and the amount of matter is the basic physical quantity.

brief introduction

Physical quantity is the relationship between quantities established by physical laws and their equations, including scalar (non-directional physical quantity), vector (directional physical quantity), tensor and dimensional (see dimensional analysis); There are independent basic quantities from which derived quantities can be derived. What is universal is called the basic constant of physics. A vector has three components and a tensor has nine components.