In this note, we are going to know about some important Units of Measurement like Fundamental Units, Derived Units, and Common Non SI Units as well. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.
Author Name: Arun Paul
Different Types of Units of Measurement
Units of measurement are defined as some quantities used to express and compare physical qualities like length, mass, time, temperature, and so on. It serves as a measuring standard and maintains consistency in scientific, technical, and everyday applications.
Fundamental Units (Base Units)
These are the basic units defined by the International System of Units (SI).
| Quantity | SI Unit | Symbol |
|---|---|---|
| Length | Meter | m |
| Mass | Kilogram | kg |
| Time | Second | s |
| Electric Current | Ampere | A |
| Temperature | Kelvin | K |
| Amount of Substance | Mole | mol |
| Luminous Intensity | Candela | cd |
Derived Units
These are formed by combining fundamental units.
| Quantity | SI Unit | Symbol |
|---|---|---|
| Area | Square meter | m² |
| Volume | Cubic meter | m³ |
| Speed/Velocity | Meter per second | m/s |
| Acceleration | Meter per second² | m/s² |
| Force | Newton | N (kg·m/s²) |
| Pressure | Pascal | Pa (N/m²) |
| Energy | Joule | J (N·m) |
| Power | Watt | W (J/s) |
| Electric Charge | Coulomb | C (A·s) |
| Frequency | Hertz | Hz (1/s) |
Common Non SI Units
These are frequently used but not part of the SI system.
| Quantity | Unit | Symbol | SI Equivalent |
|---|---|---|---|
| Length | Inch | in | 1 in = 0.0254 m |
| Length | Foot | ft | 1 ft = 0.3048 m |
| Length | Mile | mi | 1 mi = 1.609 km |
| Mass | Gram | g | 1 g = 0.001 kg |
| Mass | Pound | lb | 1 lb = 0.4536 kg |
| Time | Minute | min | 1 min = 60 s |
| Time | Hour | h | 1 h = 3600 s |
| Energy | Calorie | cal | 1 cal = 4.184 J |
| Temperature | Celsius | °C | K = °C + 273.15 |