♦ Physical Quantity • The quantities which can be measured by an instrument or anything which can be expressed in terms of numbers which describes the laws of Physical World, known as Physical Quantity.• For example, the physical quantity ‘Time’ can be quantified as ns, where n is the numerical value and s (second) is the unit. • A physical quantity possesses at least two characteristics in common….. namely • There are two main types of physical quantity, they are …… ◘ On the basis of direction and their magnitude there are other types of physical quantity include the vector quantity and scalar quantity. Note :- |
♦ Fundamental or Base Quantities • Those physical quantities which are independent in nature or rather we can say they do not depend on other physical quantities are known as fundamental or base physical quantities.• Example :-Length, Electric Current, Mass, Time, Temperature, Luminous intensity. |
♦ Derived Quantities All the physical quantities which are not the base quantities or fundamental quantities but are depend upon the fundamental quantities are known as derived quantities.• Derived quantities cannot be measured directly. They can only be computed. As because they are derived from two or more than two fundamental quantities. •Example :- Density, Force, Pressure Area, Velocity etc. • For an example the derived quantitites Velcity derived from two fundamental unit or base unit namely .. • Velocity = Distance / Time |
♦ Supplementary Quantity • There are also two physical quantities which are neither fundamental nor derived. These quantities are called supplementary quantities• Example :- Plane angles and Soild angles |
List of the Seven Fundamental Quantities | ||
---|---|---|
S.No. | Fundamental Quantity | SI Unit |
1. | Length | Metre (M) |
2. | Mass | Kg |
3. | Time | Second (s) |
4. | Current | Ampere (A) |
5. | Temperature | Kelvin |
6. | Luminous Intensity | Candela |
7. | Amount of substance | Mole |
Two Supplementary Quantity | ||
---|---|---|
8. | Plane angle | Radian |
9. | Soild angle | Steradian |
List of some Derived Quantities | |||
---|---|---|---|
S.No | Quantity | Formula | SI Unit |
1. | Magnetic Field | Force / (Electric Current x Displacement) | N amp^{-1}m^{– 1} or Tesla or Weber / m^{2} |
2. | Density | Mass/Volume | kgm^{– 3} |
3. | Area of Rectangle | Length x Breadth | m^{2} |
4. | Velocity | Distance / Time | ms^{ – 1} |
5. | Area of Square | (side)^{2} | m^{2} |
6. | Accleration | Change in Velocity / Time | ms^{-2} |
7. | Area of Triangle | 1/2 x Base x Height | m^{2} |
8. | Force | Mass x Acceleration | N |
9. | Work | Force x Distance | N.m or Jule |
10 | Pressure | Force / Area | N/m^{2}, or kg·m^{−1} s ^{−2} |
11 | Linear momentum | Mass x Velocity | kg·m^{−1} |
12 | Volume of Cuboid | Length x Breadth x Height | m^{3} |