SI Units:
- SI units are internationally accepted units used by all scientists.
- “SI” stands for Système International d’Unités.
How Are Physical Quantities Represented?
- Physical quantities are represented using symbols and units.
- Quantities are meaningless without appropriate units.
Two Main Types of Quantities:
- Basic (Fundamental) Quantities
- Derived Quantities
Basic Quantities, Units, and Symbols:
Basic quantities are quantities that can not be defined in terms of the other.
There is no combinations of different units.
- Length: Measured in meters (m)
- Mass: Measured in kilograms (kg)
- Time: Measured in seconds (s)
- Temperature: Measured in Kelvin (K)
Derived Quantities, Units, and Symbols:
Derived are quantities that can be defined in terms of the other
There are combinations of two or more units
- Area: Measured in square meters (m²)
- Density: Measured in kilograms per cubic meter (kg/m³)
- Concentration: Measured in moles per cubic meter (mol/m³)