A unit is a standard quantity used to express a physical quantity.
Importance of Units in Measurement:
- Units help compare measurements.
- Without units, measurements become meaningless.
- Example: Saying “length is 5” is unclear, but “length is 5 cm” is meaningful.
Fundamental Units:
- Units that are independent and cannot be derived from other units.
- Example: meter (m) for length, kilogram (kg) for mass, second (s) for time.
Derived Units:
- Units obtained from fundamental units.
- Example: Newton (N) = kg·m/s² (force), Joule (J) = kg·m²/s² (energy).
