19. Why do we have different units for the same physical quantity?
(3)
Hint: In the different systems of units, a quantity has different units.
The value of any given physical quantity may vary over a wide range, therefore, different units of the same physical quantity are required e.g., the length of a pen can be easily measured in cm, the height of a tree can be measured in meters, the distance between two cities can be measured in kilometres and distance between two heavenly bodies can be measured in a light year.
