International System of Units
It is build upon seven fundamental units. These are kilogram, meter, ampere, second, mole Kelvin and candela.
Basic Units
In SI unit System the seven quantities are known to be basic.
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Base quantity
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Name
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symbol
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Length
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meter
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m
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Mass
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kilogram
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kg
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Time
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second
|
s
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Electric current
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ampere
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A
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Thermodynamic temperature
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Kelvin
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K
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Amount of substance
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mole
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mol
|
|
Luminous intensity
|
candela
|
cd
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Meter
Up until the year 1983, the meter was described as 1,650,763.73 wavelengths in a vacuum of the orange-red line of the spectrum of krypton-86. As then, it is equivalent to the distance travelled by light in vacuum in 1/299,792,45 of a second.
Second
The second is described like the duration of 9,192,631,770 cycles of the radiation connected with a particular transition of the Cesium-133 atom.
Kilogram
For the kilogram the standard is a cylinder of platinum-iridium alloy kept by International Bureau of Weights and Measures at Paris. The kilogram is the only base unit till defined by a physical object.
Kelvin
The Kelvin is described like the fraction 1/273.16 of the thermodynamic temperature of the triple point of water, which is, the point at which water compose an interface of the solid, liquid & vapour. This is described as .01oC on the Centigrade scale & 32.02oF on Fahrenheit scale. The temperature 0oK is known as the "absolute zero".
Ampere
The Ampere is described as that current, if maintained in each two long parallel wires separated by a distance of one meter, would generate a force, among the two wires, of 2 x 10-7 Newton, for each meter of length.
Candela
The Candela is described as the luminous intensity of 1/600,000 of a square meter of a cavity at freezing platinum (2,042 ok)'s temperature.
Mole
The mole is described as the amount of substance of a system that have as many elementary entities as there are as several atoms in 0.012 kilogram of the Carbon-12.
Joule
Joule is described as the energy consumed in moving an item of one kg through a distance of one meter. One joule is equal to the 0.7376 foot pound-force & .2388 calories.
Watt
Watt is described as the "Rate of doing work."
One watt =1 joule/second
One watt is equal to 0.7376 ft--lbf/s or equivalently 1/745.7 horsepower.