Dimensions of Physical Quantities

 

Dimension is used in science to deduce the nature of a physical quantity.

The dimension of the fundamental quantities are shown in the diagram above. 

Remember that the combination of two or more fundamental quantities gives us a derived quantity. Therefore the dimension of derived quantities will also be gotten from

the dimensions of fundamental quantities. Examples are shown below:

1. Area (A) = length x breadth

Dimension of Area = L X L = L²

2. Volume (V) = length x breadth x height

Dimension of Volume = L X L X L = L³

3. Density = mass/volume

Dimension of density = M/L³ = ML^-3

4. Velocity = displacement/time

Dimension of velocity = L/T = LT^-1

5. Acceleration = velocity/time

Dimension of acceleration = L/T/T = LT^-2

6. Force = mass x acceleration

Dimension of force = M x LT^-2 = MLT^-2

7. Energy or Work = force x distance

Dimension of energy or work = MLT^-2 X L = ML²T^-2

8. Power = Work/time

Dimension of power = ML²T^-2/T = ML²T^-3

9. Pressure = force/area

Dimension of pressure = MLT^-2/L² = ML^-1T^-2

10. Momentum = mass x velocity

Dimension of momentum = M x LT^-1 = MLT^-1