# Physics: Fundamental, derived quantity, Units, and Dimensions.

Fundamental Vs Derived quantity

### Fundamental quantities

These are independent quantities with units. The dimension of a physical quantity indicates how it is made up in terms of S.I base quantity. In other words, the physical quantities is said to have been expressed in terms of fundamental units [Length (L), Mass (M), Time (T), kelvin (k), mole etc].

Quantity Dimension
length         L
Mass          M
Time           T
Kelvin        K
Mole          m

Derived quantities:
These are obtained by some simple combinations of the fundamental quantities and units. They are thus, dependent on the fundamental quantities and units. Example of the derived quantities, their derivation and their units are summarised in the table below:

 Derived quantity Derived unit Dimension Area  (length x breadth) m^2 L^2 Volume(length x breadth x height) m^3 L^3 Density (Mass/volume) kg/m^3 M/L/L Velocity (Displacement/time) m/s L/T Acceleration (Velocity/time) m/s/s L/T/T force (Mass x acceleration Newton (N) ML/T/T Energy & work (force x distance). joules ML^2/T/T power (work/time) joules/s ML^2/T/T/T Momentum (Mass x velocity) kg m/s ML/T Pressure  (force/area) N/m^2 ? Frequency (no of oscillation/time) 1/s 1/T

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Exercise
:
What is the dimension of pressure?

Conclusion

A  derived quantity is derived from fundamental quantity, simple and short, comprende? If you have any question, comment. All comments are appreciated.