- A derived quantity is a Physics quantity that is not a base quantity. It is the quantities which derived from the base quantities through multiplying and/or dividing them.
- For example, speed is defined as the rate of change of distance, Mathematically, we write this as Speed = Distance/Time. Both distance and time are base quantities, whereas speed is a derived quantity as it is derived from distance and time through division.

**Example**

(Speed is derived from dividing distance by time.)

### Derived Quantities That You Need to Know in SPM

- Table below shows the derived quantities that you need to know in SPM. You need to know the equation of all the quantities, so that you can derive their unit from the equation.
- If you find it difficult to memorise all these equations, you can skip it now because you are going to learn all of them in the other chapter.

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### SI unit

- The International System of Units (abbreviated SI from the French language name Système International d'Unités) is the modern form of the metric system.
- It is the world's most widely used system of units, both in everyday commerce and in science.

### Derived Unit

- The derived unit is the unit of a derived quantity. It is a combination of base units through multiplying and/or dividing them.
- For instance, speed is defined as the rate of distance change, and in mathematics, we write speed = distance/time. The unit of distance and time are meter (m) and second (s) respectively. Therefore, the unit of speed = m/s or ms
^{-1}.