Units Used in this Site.
Please note:
Genesis 11:1-9 (New International Version)
The Tower of Babel
1 Now the whole world had one language and a common speech.
5 But the LORD came down to see the city and the tower that the men were building.
6 The LORD said, "If as one people speaking the same language they have begun to do this, then nothing they plan to do will be impossible for them.
7 Come, let us go down and confuse their language so they will not understand each other."
8 So the LORD scattered them from there over all the earth, and they stopped building the city.
9 That is why it was called Babel -because there the LORD confused the language of the whole world. From there the LORD scattered them over the face of the whole earth.
At present we have a Global Babylonian Confusion with regard to people using different units to express weight, length, volume, energy, power etc. With the result that planes fall out of the sky, space programs fail and mankind is not able to discuss the Global Energy Situation coherently because they just don't understand each other.
TRIVIA: For those who want some proof that physicists are human, the proof is in the idiocy of all the different units which they use for measuring energy.
The Character of Physical Law (1967) R.P. Feynman.
Energy may be expressed in many different units, ranging from the British Thermal Unit (BTU) in the English System to the erg in the cgs system and the joule in SI (Systeme Internacionale) units. We have selected the SI units as the system of units because of its global use in science, trade and industry and to make it easier to compare different "energy resources" and "energy consumptions" globally.
The International System of Units (abbreviated SI from the French Le Système International d'Unités) is the modern form of the metric system and is generally a system devised around the convenience of the number ten. It is the world's most widely used and oldest system of measurement, both in everyday commerce and in science.
TRIVIA? :
Three nations have not officially adopted the International System of Units as their primary or sole system of measurement: Liberia, Myanmar and the United States.
The system is nearly universally employed, and most countries do not even maintain official definitions of any other units. A notable exception is the United States, which continues to use customary units in addition to SI. In the United Kingdom, conversion to metric units is government policy, but the transition is not quite complete. Those countries that still recognise non-SI units (e.g., the US) have redefined their traditional non-SI units in terms of SI units.
The International System of Units, (SI system).
(abbreviated SI from the French Le Système International d'Unités)
The international system of units SI system consists of a set of units together with a set of prefixes. The units of SI can be divided into two subsets. There are seven base units: Each of these base units represents, at least in principle, different kinds of physical quantities. From these seven base units, several other units are derived. In addition to the SI units, there is also a set of non-SI units accepted for use with SI.
| SI base units[9] | ||||
|---|---|---|---|---|
| Name | Symbol | Quantity | Definitions | |
| meter | m | length | The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. See history of the meter. | |
| kilogram | kg | mass | The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram. | |
| second | s | time | The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. | |
| ampere | A | electric current | The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length. | |
| kelvin | K | thermodynamic temperature | The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. | |
| candela | cd | luminous intensity | The candela is 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. | |
| mole | mol | amount of substance | The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is "mol." | |
| Derived units from the SI base units, that will be used in this Website | ||||
| Name | Symbol | Quantity | Expression in terms of other units | Expression in terms of SI base units |
| joule | J | energy, work, heat | N.m = C.V = W.s | m2.kg.s-2 |
| watt | W | power, radiant flux | J/s = V.A | m2.kg.s-3 |
| hertz | Hz | frequency | 1/s | |
| newton | N | force, weight | kg.m/s2 | |
| pascal | Pa | pressure, stress | N/m2 | m-1kg.s-2 |
| volt | V | voltage,electrical potencial difference | W/A = J/C | m2.kg.s-3A-1 |
| °Celcius | °C | temperature | K ? 273.15 | |
Big and Small Numbers, METRIC PREFIXES
Metric prefixes are pretty easy to understand and very handy for metric conversions. You don't have to know the nature of a unit to convert, for example, from kilo-unit to mega-unit. All metric prefixes are powers of 10. The most commonly used prefixes are highlighted in the table.
| Prexis | Symbol | Factor |
|---|---|---|
| yotta | Y | 1024 = 1,000,000,000,000,000,000,000,000 |
| zetta | Z | 1021 = 1,000,000,000,000,000,000,000 |
| exa | E | 1018 = 1,000,000,000,000,000,000 |
| peta | P | 1015 = 1,000,000,000,000,000 |
| tera | T | 1012 = 1,000,000,000,000 |
| giga | G | 109 = 1,000,000,000 |
| mega | M | 106 = 1,000,000 |
| kilo | k | 103 = 1,000 |
| hecto | h | 102 = 100 |
| deka | da | 101 = 10 |
| deci | d | 10-1 = 0.1 |
| centi | c | 10-2 = 0.01 |
| milli | m | 10-3 = 0.001 |
| micro | μ | 10-6 = 0.000,001 |
| nano | n | 10-9 = 0.000,000,001 |
| pico | p | 10-12 = 0,000,000,000,001 |
| femto | f | 10-15 = 0.000,000,000,000,001 |
| atto | a | 10-18 = 0.000,000,000,000,000,001 |
| zepto | z | 10-21 = 0.000,000,000,000,000,000,001 |
| yocto | y | 10-24 = 0.000,000,000,000,000,000,000,001 |
Most people even in the countries where metric system is used only know the most important metric prefixes like 'kilo' and 'milli'. They are very handy for understanding metric conversions. The prefixes like 'zepto' or 'yotta' are very specific and used mostly in science.
