Fundamental and Derived units | Supplementary unit | Different Units System in Som and Mechanics:
CGS System
The Centimetre Gram Second system of units is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time.
MKS System:
MKS is the system of units based on measuring lengths in meters, mass in kilograms, and time in seconds.
FPS System:
The foot pound second system or FPS system is a system of units built on the three fundamental units foot for length, pound for mass and second for time.
S.I System:
International System of Units (SI) is the unit system adopted by the General Conference on Weights and Measures in 1960 and recommended for use in all scientific and technical fields.
Physical Quantities:
A physical quantity is a quantity that can be measured.
There are two types of physical quantities:
1. Fundamental Quantities
2. Derived Quantities
1. Fundamental Quantities:
The physical quantities which do not depend on any other physical quantities for their measurements.
S.I unit system consists of seven fundamental units:
1. Length in meter(m)
2. Mass in Kilogram(kg)
3. Time in second(s)
4. Electric Current in ampere(A)
5. Thermodynamics Temperature in Kelvin(k)
6. Amount of substance in Mole(mol.)
7. Luminous Intensity in candela(Cd.)
2. Derived Quantities:
The quantities, which can be expressed in terms of the fundamental quantities are called derived quantities. For example: density, velocity, Pressure etc.
There are also Two supplementary unit which cannot drived from the fundamental units.
1. Plane angle in Radian(rad.)
2. Solid angle in Steredian(Sd.)
Basic concepts for exam: unit change concept table:
Mili - 1000000
Centi - 100000
Deci - 10000
Meter(unit: m,gram,liter) - 1000
Deca - 100
Hecto - 10
Kilo - 1
Important prefix for exams:(see pdf notes also)
Tera - 10^12
Giga - 10^9
Mega - 10^6
Kilo - 10^3
Centi - 10^-2
Milli - 10^-3
Micro - 10^-6
Nano - 10^-9
Pico - 10^-12