Measurements

Classification of physical quantities

1. Fundamental quantities - Not derived from other quantities.
   E.g. length, mass and time.
2. Derived quantities - Derived from fundamental quantities.
   E.g. velocity, area and acceleration.
3. Scalar quantities - Have magnitude, Not direction.
   E.g. velocity, work and power.
4. Vector quantities - Have both magnitude and direction.
   E.g. force, velocity and acceleration.

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Unit is the standard measure of a quantity. There are 7 basic units.
E.g. time, length, mass, electric current, thermodynamic temperature, amount of substance, luminous intensity.

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Metric system