Concepts
Physical Quantities and Their Measurement:
Fundamental Units:-
These units can neither be derived from one another nor can be further resolved into any other units. Seven fundamental units of the S.I. system
| Physical quantity | Name of the unit | Symbol of the unit |
| Time | Second | S |
| Mass | Kilogram | kg |
| Length | Meter | m |
| Temperature | Kelvin | K |
| Electric current | Ampere | A |
| Luminous intensity | Candela | Cd |
| Amount of substance | Mole | Mol |
Derived Units:-
These units are the function of more than one fundamental unit
| Quantity with Symbol | Unit (S.I.) | Symbol |
| Velocity (v) | Metre per sec | ms-1 |
| Area (A) | Square metre | m2 |
| Volume (V) | Cubic metre | m3 |
| Density (r) | Kilogram m-3 | Kg m-3 |
| Energy (E) | Joule (J) | Kg m2s-2 |
| Force (F) | Newton (N) | Kg ms-2 |
| Frequency (n) | Hertz | Cycle per sec |
| Pressure (P) | Pascal (Pa) | Nm-2 |
| Electrical charge | Coulomb (C) | A-s (ampere – second) |
Measurement of Temperature
Three scales of temperature
- Kelvin scale (K)
- Degree Celsius scale (oC)
- Degree Fahrenheit scale (oF)
Relations between the scales:
- oF = 9/5(oC) + 32
- K = oC + 273
0 K temperatures is called absolute zero.