1.2 Base and Derived Physical Quantities
Physics is a science of the physical world where we interact with many different types of material objects. These objects are described in terms of their measurable features, known as physical quantities, such as length, breadth, thickness, mass, volume, density, time, and temperature.
Out of these, scientists have selected some quantities to play a key role. They are called base quantities. All the quantities which can be described in terms of one or more base quantities are called derived physical quantities. For example, speed is a derived quantity which depends on distance and time, both of which are base quantities. Density of a material is described in terms of mass and volume.