Physics deals with objects or phenomena. Therefore, to understand and properly apply these objects and phenomena, some of their attributes or properties need to be quantified or measured. These properties are called the physical quantities.
Physical quantities are properties or attributes of objects or phenomena that can be quantified or measured. These quantities describe various aspects of the physical world, including length, mass, time, temperature, electric charge, and many others.
Physical quantities provide measurable properties of matter and energy, enabling scientists and engineers to formulate theories, perform experiments, and develop technologies.
A physical quantity must contain a numerical value and a unit of measurement.
The unit could be the submultiple or multiple of the SI unit. Therefore, 
is a physical quantity.
Physical quantities are broadly classified into two categories:
Fundamental quantities
Derived quantities
Let's examine each of the classifications.
Fundamental quantities are also called the base or basic quantities. They are the basic measurable quantities that do not depend on other quantities. There are seven fundamental quantities and they are listed with their SI units in the table below:
The units of fundamental quantities are called the base units. The units of other quantities are based on them.
These are quantities that are obtained by combining fundamental quantities through mathematical operations. Some examples of derived quantities with their derivations and units are listed in the table below:
From the examples in the table above, we can observe that the derived quantities are formed by combining fundamental quantities, majorly length, mass, and time.
Physical quantities can also be categorised into:
Scalar quantities: These are quantities that have only magnitude but no direction. Scalar quantities are described by only a numerical value and a unit.
Examples of scalar quantities are length, time, mass, temperature, density, work, and so on.
Vector quantities: These are physical quantities that have both magnitude and direction. Diagrammatically, they are represented by arrows, where the length of the arrow indicates the magnitude, and the arrowhead shows the direction.
Examples of vector quantities include displacement, velocity, force, momentum, electric field, and so on.
In physics, the English and Greek alphabets are used to represent or denote physical quantities.
