Wednesday, November 29, 2023

# Unit defination

Units:
The measurement of a physical quantity is one of the most important functions in engineering. For measurement of a physical quantity a standard of reference is necessary. This reference is called unit. Or units are accepted standard for measuring a quantity. Example: The length of the table is 6 meters, it means standard adopted is meter and numerical value is 6.

Classifications of Units:
Units are mainly classified into the following types.
1) Fundamental Units
2) Derived Units

Fundamental Units:
Every physical quantity can be expressed in terms of fundamental quantities length, mass and time. The units of these fundamental quantities are called fundamental units.

Derived Units:
Units which are derived from fundamental units are called derived units. Or the units which are also expressed in other units called as derived units.
Example: unit of velocity, acceleration, pressure, area etc.

System of Units:
There are three systems of units, which are commonly used and internationally recognized.
1) C.G.S. System
2) F.P.S. System
3) M.K.S. System

1) C.G.S. System: In this system, the fundamentals units of length, mass and time are centimeter, gram and second.
2) F.P.S. System: In this system, the fundamentals units of length, mass and time are foot, found and second.
3) M.K.S. System: In this system, the fundamentals units of length, mass and time are meter, kilogram and second.