[It's Relative]
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The Metric SystemA reference to the world's most widely used system of measurement[The Metric System] [Values of Constants] [Conversion Factors] |
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[It's Relative]
[Language] Sponsored Link To place a link here contact the webmaster.
|
The Metric SystemA reference to the world's most widely used system of measurement[The Metric System] [Values of Constants] [Conversion Factors] |
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| Unit Type | Unit Name | Symbol | Definition |
|---|---|---|---|
| Length | metre | m | 1/299,792,458 of the distance travelled by light in a vacuum in one second |
| Mass | kilogram | kg | The mass of a Platinum-Iridium cylinder kept in Paris. |
| Time | second | s | The duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the Caesium 133 atom. |
| Electric Current |
ampere | A | The amount of current that if maintained in two parallel rectilinear conductors (of infinite length and negligible circular cross-section) placed 1 metre apart in a vacuum, would produce a force between these conductors equal to 2 × 10-7 newton per metre. |
| Temperature | kelvin | K | The fraction 1/273.16 of the thermodynamic temperature at the triple point of water. |
| Amount of Substance |
mole | mol | The amount of substance which contains as many elementary units as there are atoms in 12 grams of pure Carbon 12. |
| Luminous Intensity |
candela | cd | The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian. |
| Angle | radian | rad | The angle subtended at the centre of a circle by an arc of the circumference equal in length to the radius of the circle. |
| Solid Angle | steradian | sr | The solid angle subtended at the centre of a sphere of radius r by a portion of the surface of the sphere having an area r2. |
For example, kilo- means 1000 and can be used to denote 1000 of any unit (eg. 1000 metres is a kilometre, written as km). Also, milli- means 1/1000th and can be used to denote 1/1000th of any unit (1/1000th of a metre is a millimetre, written as mm).
Note that the case of the prefix is important. M is mega, while m is milli.
| Prefix Name | ||
|---|---|---|
| tera | T | 1012 |
| giga | G | 109 |
| mega | M | 106 |
| kilo | k | 103 |
| 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 |
The Fundamental Units are shown in red.
Note that the case of the unit is important. K is a degree Kelvin, k is kilo- (1000).
| Unit Type | Unit Name | Fundamental Units | |
|---|---|---|---|
| Length | metre | m | |
| Area | square metre | m2 | |
| Volume | cubic metre | m3 | |
| Time | second | s | |
| Frequency | hertz | Hz | s-1 |
| Velocity | metre per second | m s-1 | |
| Acceleration | metre per second squared | m s-2 | |
| Kinematic Viscosity | square metre per second | m2 s-1 | |
| Mass | kilogram | kg | |
| Density | kilogram per cubic meter | kg m-3 | |
| Moment of Inertia | kilogram square meter | kg m2 | |
| Force / Weight | newton | N | kg m s-2 |
| Momentum / Impulse | newton second | N s | kg m s-1 |
| Energy / Work / Torque | joule | J | kg m2 s-2 (N m) |
| Power | watt | W | kg m2 s-3 (J s-1) |
| Sound Intensity | watt per square meter | W m-2 | |
| Surface Tension | newton per meter | N m-1 | |
| Pressure | pascal | Pa | N m-2 |
| Compressibility | square meter per newton | m2 N-1 | |
| Dynamic Viscosity | newton second per square meter | N s m-2 | |
| Temperature | kelvin | K | |
| Thermal Conductivity | watt per metre per kelvin | W m-1 K-1 | |
| Entropy / Heat Capacity | joule per kelvin | J K-1 | |
| Specific Heat Capacity | joule per kilogram per kelvin | J kg-1 K-1 | |
| Amount of Substance | mole | mol | |
| Ionic Strength | mole per kilogram | mol kg-1 | |
| Molar Volume | cubic metre per mole | m3 mol-1 | |
| Molar Mass | kilogram per mole | kg mol-1 | |
| Luminous Intensity | candela | cd | |
| Luminance | candela per square metre | cd m-2 | |
| Solid Angle | steradian | sr | |
| Luminous Flux | lumen | lm | cd sr |
| Illumination | lux | lx | cd sr m-2 |
| Electric Current | ampere | A | |
| Magnetic Field Strength | ampere per metre | A m-1 | |
| Electric Current Density | ampere per square metre | A m-2 | |
| Magnetic Moment | ampere square metre | A m2 | |
| Electric Charge | coulomb | C | A s |
| Dipole Moment | coulomb meter | C m | |
| Surface Charge Density | coulomb per square meter | C m-2 | |
| Volume Charge Density | coulomb per cubic meter | C m-3 | |
| Potential Difference | volt | V | kg m2 s-3 A-1 |
| Electric Field Strength | volt per meter | V m-1 | |
| Thermoelectric Power | volt per kelvin | V K-1 | |
| Magnetic Flux | weber | Wb | V s |
| Inductance | henry | H | Wb A-1 |
| Permeability | henry per meter | H m-1 | |
| Flux Density | tesla | T | kg s-2 A-1 |
| Resistance / Impedance | ohm | W | V A-1 |
| Resistivity | ohm meter | V A-1 m | |
| Capacitance | farad | F | A2 s4 kg-1 m-2 |
| Permittivity | farad per meter | F m-1 | |
| Conductance | siemens | S | F s-1 |
| Electrical Conductivity | siemens per meter | S m-1 | |
| Molar Conductivity | siemens square meter per mole | S m2 mol-1 | |
| Angle | radian | rad | |
| Power of Lens | radian per meter | rad m-1 | |
| Angular Velocity | radian per second | rad s-1 | |
| Angular Acceleration | radian per second squared | rad s-2 |
| Quantity | Value | |
|---|---|---|
| Velocity of light in a vacuum | c | 2.997 925 × 108 m s-1 |
| Boltzmann Constant | k | 1.380 54 × 10-23 J K-1 |
| Planck Constant | h | 6.625 59 × 10-34 J s |
| Gravitational Constant | G | 6.673 × 10-11 N m2 kg-2 |
| Acceleration of gravity on the Earth's surface | g | 9.806 65 m s-2 |
| Stefan Constant | s | 5.670 3 × 10-8J K-4 m-2 s-1 |
| Faraday Constant | F | 9.648 70 × 104 C mol-1 |
| Avogadro Constant | L | 6.022 52 × 1023 mol-1 |
| Charge on an electron | e | 1.602 10 × 10-19 C |
| Rest mass of electron | me | 9.109 08 × 10-31 kg |
| Hubble Constant | H | 2.5 × 10-18 m s-1 m-1 |
| Gas Constant | R | 8.314 34 J K-1 mol-1 |
Note that many of these units differ by country. This makes them of little use in a global environment, like the WORLD Wide Web or trans-national business.
| Unit | Description | Value |
|---|---|---|
| Ångström | Length (Atomic) | 1.000 × 10-10 m |
| acre | Area of Land | 4.047 × 103 m2 |
| astronomical unit | Distance Between Earth and Sun | 1.496 × 1011 m |
| atmosphere | Atmospheric Pressure on the surface of the Earth at Sea Level | 1.013 × 105 N m-2 |
| atomic mass unit | Mass of Hydrogen Atom | 1.660 × 10-27 kg |
| barrel | Volume of Oil | 0.1636 m3 |
| British thermal unit | Energy | 1.055 × 103 J |
| bushel (UK) | Volume (Dry Substances) | 3.637 × 10-2 m3 |
| bushel (USA) | Volume (Dry Substances) | 3.531 × 10-2 m3 |
| calorie | Energy | 4.184 J |
| carat | Weight | 2 × 10-4 kg |
| chain | Length | 20.12 m |
| cubic foot | Volume | 2.832 × 10-2 m3 |
| cubic yard | Volume | 0.7646 m3 |
| curie | Radioactivity | 3.7 × 1010 s-1 |
| day | Time | 8.6400 × 104 s |
| degree | Angle | 1.745 × 10-2 rad |
| degree Celsius | Temperature | 1.000 K |
| degree Fahrenheit | Temperature | 0.5556 K |
| dyne | Force | 1.000 × 10-5 N |
| electron volt | Energy (Atoms and Sub-Atomic Particles) | 1.602 × 10-19 J |
| erg | Energy | 1.000 × 10-7 J |
| fathom | Distance (Depth) | 1.8288 m |
| fluid ounce (UK) | Volume (Liquid) | 2.841 × 10-5 m3 |
| foot | Length | 0.3048 m |
| foot pound force | Energy | 1.356 × 105 J |
| gallon (UK) | Volume (Liquid) | 4.546 × 10-3 m3 |
| gallon (USA) | Volume (Liquid) | 3.785 × 10-3 m3 |
| gill (UK) | Volume (Liquid) | 1.4205 × 10-4 m3 |
| gill (USA) | Volume (Liquid) | 2.841 × 10-4 m3 |
| hectare | Area of Land | 1.000 × 104 m2 |
| hour | Time | 3.600 × 103 s |
| horsepower | Power | 7.457 × 102 W |
| hundredweight (UK) | Weight | 50.80 kg |
| inch | Length | 2.54 × 10-2 m |
| kilowatt hour | Energy | 3.600 × 106 J |
| knot | Velocity (at Sea / Flight) | 0.5114 m s-1 |
| league | Distance | 9.0885 km |
| light year | Distance (Stars / Galaxies) | 9.461 × 1012 km |
| litre | Volume (Liquid) | 1.000 × 10-3 m3 |
| mile | Distance | 1.609 km |
| mile (nautical) | Distance (Sea / Air) | 1.852 km |
| mile per hour | Velocity | 0.4704 m s-1 |
| minute | Angle | 2.909 × 10-4 rad |
| minute | Time | 60 s |
| ounce | Weight | 2.835 × 10-2 kg |
| parsec | Distance (Stars / Galaxies) | 3.084 × 1013 km |
| peck (UK) | Volume (Dry) | 9.092 × 10-3 m3 |
| peck (USA) | Volume (Dry) | 8.810 × 10-3 m3 |
| pint (UK) | Volume (Liquid) | 5.682 × 10-4 m3 |
| pint (USA) | Volume (Dry) | 5.517 × 10-4 m3 |
| pint (USA) | Volume (Liquid) | 4.735 × 10-4 m3 |
| pound | Weight | 0.4536 kg |
| pound-force | Force | 4.448 N |
| rad / röntgen | Radiation Dosage | 1.00 × 10-2 J kg-1 |
| second | Angle | 4.848 × 10-6 rad |
| square foot | Area | 9.290 × 10-2 m2 |
| square inch | Area | 6.452 × 10-4 m2 |
| square mile | Area | 2.590 × 106 m2 |
| square yard | Area | 0.8361 m2 |
| therm | Energy | 1.055 × 108 J |
| ton (UK) | Weight | 1.016 × 103 kg |
| tonne (metric ton) | Weight | 1000 kg |
| tropical year | Time | 3.156 × 107 s |
| yard | Length | 0.9144 m |