Unit: Measurement
of any physical quantity involves comparison with a certain basic, arbitrarily
chosen, internationally accepted reference standard called unit.
Fundamental or base
units: The units for the fundamental or base quantities are called fundamental or
base units.
Base quantities
and their units: The seven base quantities and their units are,
|
Sl. No.
|
Base quantity
|
Unit
|
Symbol
|
|
1
|
Length
|
Meter
|
M
|
|
2
|
Mass
|
Kilogram
|
Kg
|
|
3
|
Time
|
Second
|
Sec
|
|
4
|
Electric current
|
Ampere
|
A
|
|
5
|
Temperature
|
Kelvin
|
K
|
|
6
|
Luminous intensity
|
Candela
|
Cd
|
|
7
|
Amount of substance
|
Mole
|
Mole
|
Derived units: Derived
units are units which may be expressed in terms of base units
Some Derived Si
Units and Their Symbols:
|
Quantity
|
Unit
|
Symbol
|
Express in base units
|
|
Force
|
Newton
|
N
|
Kg-m/s2
|
|
Work
|
Joules
|
J
|
Kg-m2/s2
|
|
Power
|
Watt
|
W
|
Kg-m2/s3
|
|
Pressure
|
Pascal
|
Pa
|
Kg m-1/s2
|
