Classification of physical quantities
- Fundamental quantities - Not derived from other quantities.
E.g. length, mass and time.
- Derived quantities - Derived from fundamental quantities.
E.g. velocity, area and acceleration.
- Scalar quantities - Have magnitude, Not direction.
E.g. velocity, work and power.
- Vector quantities - Have both magnitude and direction.
E.g. force, velocity and acceleration.
Unit is the standard measure of a quantity. There are 7 basic units.
E.g. time, length, mass, electric current, thermodynamic temperature, amount of substance, luminous intensity.
| Qunatity |
SI Unit |
| Acceleration |
Metre/second square (m/s2) |
| Amount of substance |
Mole (mol) |
| Angle |
Radian (rad) |
| Angular vocity |
Radian/ second (rad/s) |
| Area |
Square Metre (m2) |
| Capacitance |
Farad (F) |
| Electric charge |
Coulomb (C) |
| Electric current |
Ampere (A) |
| Electric potential |
Volt (V) |
| Energy |
Joule (J) |
| Frequency |
Hertz (Hz) |
| Force |
Newton (N) |
| Impulse |
NewtonSecond (Ns) |
| Inductance |
Henry (H) |
| Length |
Metre (m) |
| Luminous intensity |
Candela (cd) |
| Magnetic field |
Tesla (tesla) |
| Magnetic flux |
Weber (Wb) |
| Mass |
Kilogram (kg) |
| Moment of inertia |
Kilogram square meter (Kgm2) |
| Momentum |
KilogramMeter/second (Kgm/s) |
| Power |
Watt (W) |
| Pressure |
Pascal (Pa) |
| Resistance |
Ohm (Ω) |
| Solid angle |
Steradian (Dr) |
| Time |
Second (s) |
| Temperature |
Kelvin (K) |
| Velocity |
Metre/second (m/s) |
| Volume |
Cubic metre (m3) |
| Work |
Joule (J) |
Metric system
| Ptefix |
Symbol |
Multiplier |
| deca |
da |
101 |
| hecto |
h |
102 |
| kilo |
k |
103 |
| mega |
M |
106 |
| giga |
G |
109 |
| tera |
T |
1012 |
| peta |
P |
1015 |
| exa |
E |
1018 |
| zetta |
Z |
1021 |
| yotta |
Y |
1024 |
| deci |
d |
10-1 |
| centi |
c |
10-2 |
| milli |
m |
10-3 |
| micro |
μ |
10-6 |
| nano |
n |
10-9 |
| pico |
p |
10-12 |
| femto |
f |
10-15 |
| atto |
a |
10-18 |
| zepto |
z |
10-21 |
| yocto |
y |
10-24 |
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