A physical quantity is quantity that can be measured and consist of numerical magnitude and a unit.

Physical Quantities can be classified into two types :

• The Base or Fundamental quantities
• The derived quantities

1. Base quantities
 table 1. Base quantities
Base quantities                         Name of unit                            Symbol for unit
  Length                                         meter                                            m
   mass                                        kilogram                                          kg
   time                                         second                                             s
Electric current                            ampere                                           A
temperature                                 kelvin                                             K
Amount of substance                   mole                                              Mol
Lominous intensity                      candela                                           cd





2. Derived quantities

• Derived quantities can be defined as quantities that can be derived out of the combination of the basic quantities 
• for instance a 'speed' is the ratio of a length by a time.
• An acceleration the ratio of a speed by a time, and 
• a force the multiplication of an acceleration by a mass

Physical quantity              Relation with base quantity             Symbol for unit

       Area                                           Length x width                                              m²

    Volume                                  Length x width x height                                  m³

    Speed                                         distance                                                          m·s⁻¹

                                                            ^time

MEASUREMENT : Physical Quantities

Physic is experimental study. Most experiments in physics need quantitative observation rather than qualitative observation.Quantitative observation needs some test and mesurement.

A physical quantity is quantity that can be measured and consist of numerical magnitude and a unit.

In order to test and measure physical quantities we need to define some standard measures which we everyone can agree on.  The internationally recognised authority for the definition of these standards is the Conference Generale des Poids et Measures (CGPM). 

The units by which we now measure physical quantities is called the S.I. (System International) system established in 1960. Within this system, the most commonly used set of units in physics are M.K.S (Metres, Kilograms, Seconds) system

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