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

uyi osamudiamen Lucky
August 16, 2019

**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 |

**Watch video**

__Example__

__What is the dimension of EMF?__

EMF(Electromotive Force) is a derived quantity. It is work done by the chemical force to move unit positive charge from negative terminal to positive terminal of the battery.

EMF = Workdone / charge

Work=Force * displacement

=MLT^-2 * L =ML^2T^-2

Charge=Current * time

=IT

Now,

Dimensional formula of

EMF=Work/charge

=ML^2T^-2 / IT

=ML^2T^-3I^-1

**:**

__Exercise__What is the dimension of pressure?

**Solution**

Watch how to derive the dimension of Pressure.

Get more Info:

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**Conclusion**

A derived quantity is derived from fundamental quantity, simple and short. I hcomments article was helpful. If you have any questions or comments, please don't hesitate to write it in the comments section. All comments are appreciated.

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Physics: Fundamental, derived quantity, Units, and Dimensions.
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August 16, 2019
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