Question

what are derived units? Derive the unit for the area of rectangle and speed.

Answer 1

Derived units are the units which are derived from the fundamental units. 

Area of rectangle = length×breadth
SI unit of length = m
SI unit of breadth = m
SI unit of area = m×m = m²
Dimensional formula = [M^0 L^2 T^0]

speed = distance/time
SI unit of distance = m
SI unit of time = s
SI unit of area = m/s 
Dimensional formula = [M^0 L^1 T^(-1)]

Answer 2

Derived units are the physical units which depend upon other physical units. For e.g., N (kg m/s²), ω (rad/s), etc.

Unit for area of rectangle = m × m = m²

Unit for speed = m/s

(Distance upon time)

More:-

• There are two types of physical units, viz., derived physical units and fundamental physical units.
• The units which do not depend on other units are called fundamental units. For e.g., cd (candela), m (metres), etc.
• Physical quantities are in the form of P = nu where n = numerical value and u is the unit and P stands for physical quantity.