Basic quantities are physical quantities that cannot be expressed in terms of other quantities. They are also known as fundamental quantities or base quantities. The seven basic quantities in the International System of Units (SI) are:

* Length (meter)

* Mass (kilogram)

* Time (second)

* Electric current (ampere)

* Thermodynamic temperature (kelvin)

* Amount of substance (mole)

* Luminous intensity (candela)

Derived Quantities

Derived quantities are physical quantities that can be expressed in terms of basic quantities. For example, the derived quantity of speed can be expressed as the basic quantity of length divided by the basic quantity of time. Some other examples of derived quantities include:

* Area (length × length)

* Volume (length × length × length)

* Density (mass / volume)

* Force (mass × acceleration)

* Energy (force × distance)

* Power (energy / time)

Relationship between Basic and Derived Quantities

The basic quantities are the foundation of the SI system of units. All other quantities can be derived from the basic quantities. The relationships between the basic and derived quantities are defined by mathematical equations. For example, the equation for speed is:

```

speed = distance / time

```

This equation shows that speed is a derived quantity that is related to the basic quantities of distance and time.

Units of Measurement

The units of measurement for basic and derived quantities are also defined by the SI system of units. The units for the basic quantities are the meter, kilogram, second, ampere, kelvin, mole, and candela. The units for derived quantities are derived from the units for the basic quantities. For example, the unit for speed is the meter per second (m/s).

The SI system of units is a coherent system of units. This means that the units for all quantities are related to each other in a consistent way. This allows for easy conversion between different units of measurement.