Enumerate and describe the different system of measurement?

Answer 1

Systems of measurementMTS unitsSee also: Mesures usuelles

During the twentieth century, the Soviets and French briefly used a variant of the metric system where the base unit of mass was thetonne.

FFF unitsMain article: FFF system

UnitDimensionDefinitionSI Valuefurlonglength660 ft201.168 mfirkin[1]mass90 lb40.8233 kgfortnighttime14 days1,209,600 s

Most countries use the International System of Units (SI). In contrast, the humorousFurlong/Firkin/Fortnight system of units of measurement draws attention by being extremely old fashioned, and off-beat at the same time.[2]

One furlong per fortnight is very nearly 1 centimetre per minute (to within 1 part in 400). Indeed, if the inch were defined as 2.54 cm rather than 2.54 cm exactly, it would be 1 cm/min. Besides having the meaning of "any obscure unit", furlongs per fortnight have also served frequently in the classroom as an example on how to reduce a unit's fraction. The speed of light may be expressed as being roughly 1.8 terafurlongs per fortnight.[3][4]

SI-imperial hybridsIn the US, mongrel units are sometimes formed by a combination of traditional units, which are widely used, and metric units. Thus, "grams per fluid ounce" and "grams per pound of body weight" are common units used in sports nutrition, for example, to express theconcentration of carbohydrate in a beverage.

A hybrid standard quantity used in mining is the assay ton (AT), which is as many milligrams as there are troy ounces in a ton: 29.17 grams if the ton used is the short ton, and 32.67 g if the ton used is the long ton. So to find how many ounces of gold are in a ton of rock, one measures the number of milligrams of gold in an assay ton of rock.

There are also reports of engineers using base-ten SI prefixes in combination with Imperial or US customary units, for example thekiloyard (914.4 m). The kip or kilopound is regularly used in structural engineering. Similarly, the kilofoot is quite common in UStelecommunication engineering, as significant distances in cable route planning are usually given in thousands of feet. Instruments likeoptical time-domain reflectometers usually have an option to display results in kilofeet. Perhaps most common is the use of the thou or mil, defined as 1/1,000 of an inch (25.4 µm), frequently used in the manufacturing industry and to measure the thickness of very thin materials like film and plastic sheeting. A related unit is the circular mil, used for measuring the cross-sectional area of wire.

In the UK, it is still (2007) not uncommon to find the "metric foot" in use in the domestic refurbishment market. A metric foot is 30 cm and usually it is used with lumber (timber in the UK) that is only available in metric yards or 90 cm multiples (see metric inch below). Its square form is also common in some fields: for example, carpet and other flooring materials, when supplied in "tiles" (squares), are often supplied in this size.

In commercial office fitout in the UK, most suspended ceilings and raised floors are based on a 60 cm module, or 2 "metric feet".

A useful unit when working with optical pathway lengths in the lab is the one foot per nanosecond approximation for the speed of light. In electronic circuitry, where the velocity of propagation is somewhat slower than the speed of light in a vacuum, similar approximations can be used for "signal races" in the circuitry. (See light-nanosecond below.)

Derived unitsThere are some obscure metric units: with arbitrary units and prefixes, a common unit can be expressed with an unfamiliar term. Among physicists there is the in-joke replacing common units with uncommon units, as in velocity: metres per second is equivalent tohertz per dioptre (Hz/dpt). In this case, the reciprocal values of metre and second - dioptre and hertz, respectively - are used to contrive the same unit. The becquerel could also be used instead of hertz, as it is a measure of aperiodic events per time, instead of the periodic events per time measured by the hertz. Planck UnitsMain article: Planck units

Planck units, sometimes called "natural units", were proposed in 1899 by the physicist Max Planck, and are defined by setting certainphysical constants to equal 1. In this system, one metre equals about 6.187 x 1034 Planck length units, and one second equals 1.854 x 1043 Planck time units. The speed of light is, by definition, exactly 1 Planck length / Planck time.