FFF System
Encyclopedia
The Furlong/Firkin/Fortnight (FFF) system is a set of units that uses impractical measurements not seriously deemed suitable for scientific or engineering use. The length unit of the system is the furlong
, the mass unit is the mass of a firkin
of water, and the time unit is the fortnight
. Like the SI or metre-kilogram-second system
, there are derived units for velocity
etc.
The FFF system is mainly a humorous system of units and is not used in practice, although it has been used as an example in discussions of the relative merits of different systems of units. Some of the FFF units, notably the microfortnight, have been used jokingly in computer science. Besides having the meaning "any obscure unit," furlongs per fortnight have also served frequently in classroom examples of unit conversion and reducing a unit's fraction.
s. This has become a joke in computer science because in the VMS
operating system
, the TIMEPROMPTWAIT variable, which holds the time the system will wait for an operator to set the correct date and time at boot if it realizes that the current value is bogus, is set in microfortnights. This is because the computer uses a loop
instead of the internal clock which has not been activated yet to run the timer. In a further twist, the documentation notes that "[t]he time unit of micro-fortnights is approximated as seconds in the implementation."
Millifortnights (about 20 minutes) and nanofortnights (1.2096 milliseconds) have also been used occasionally in computer science
, usually in an attempt to be deliberately over-complex and obscure.
Thus:
Furlong
A furlong is a measure of distance in imperial units and U.S. customary units equal to one-eighth of a mile, equivalent to 220 yards, 660 feet, 40 rods, or 10 chains. The exact value of the furlong varies slightly among English-speaking countries....
, the mass unit is the mass of a firkin
Firkin
A firkin is an old English unit of volume. The name is derived from the Middle Dutch word vierdekijn, which means fourth, i.e. a quarter of a full-size barrel.Nor need you mind the serial ordealOf being watched from forty cellar holes...
of water, and the time unit is the fortnight
Fortnight
The fortnight is a unit of time equal to fourteen days, or two weeks. The word derives from the Old English fēowertyne niht, meaning "fourteen nights"....
. Like the SI or metre-kilogram-second system
International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...
, there are derived units for velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
etc.
The FFF system is mainly a humorous system of units and is not used in practice, although it has been used as an example in discussions of the relative merits of different systems of units. Some of the FFF units, notably the microfortnight, have been used jokingly in computer science. Besides having the meaning "any obscure unit," furlongs per fortnight have also served frequently in classroom examples of unit conversion and reducing a unit's fraction.
Base units and definitions
| Unit | Abbreviation | Dimension | SI Si Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system... unit |
Imperial unit |
|---|---|---|---|---|
| furlong Furlong A furlong is a measure of distance in imperial units and U.S. customary units equal to one-eighth of a mile, equivalent to 220 yards, 660 feet, 40 rods, or 10 chains. The exact value of the furlong varies slightly among English-speaking countries.... |
fur | length | 201.168 m Metre The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology... |
220 yard Yard A yard is a unit of length in several different systems including English units, Imperial units and United States customary units. It is equal to 3 feet or 36 inches... s |
| firkin Firkin A firkin is an old English unit of volume. The name is derived from the Middle Dutch word vierdekijn, which means fourth, i.e. a quarter of a full-size barrel.Nor need you mind the serial ordealOf being watched from forty cellar holes... |
fir | mass | 40.8233133 kg Kilogram The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water... |
90 lb |
| fortnight Fortnight The fortnight is a unit of time equal to fourteen days, or two weeks. The word derives from the Old English fēowertyne niht, meaning "fourteen nights".... |
ftn | time | 1,209,600 s Second The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock.... |
14 days |
Microfortnight
One microfortnight is equal to 1.2096 secondSecond
The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
s. This has become a joke in computer science because in the VMS
OpenVMS
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
, the TIMEPROMPTWAIT variable, which holds the time the system will wait for an operator to set the correct date and time at boot if it realizes that the current value is bogus, is set in microfortnights. This is because the computer uses a loop
Busy waiting
In software engineering, busy-waiting or spinning is a technique in which a process repeatedly checks to see if a condition is true, such as whether keyboard input is available, or if a lock is available. Spinning can also be used to generate an arbitrary time delay, a technique that was necessary...
instead of the internal clock which has not been activated yet to run the timer. In a further twist, the documentation notes that "[t]he time unit of micro-fortnights is approximated as seconds in the implementation."
Millifortnights (about 20 minutes) and nanofortnights (1.2096 milliseconds) have also been used occasionally in computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, usually in an attempt to be deliberately over-complex and obscure.
Furlong per fortnight
One furlong per fortnight, a speed which would be barely noticeable to the naked eye, converts to:- 1.663 metre per secondMetre per secondMetre per second is an SI derived unit of both speed and velocity , defined by distance in metres divided by time in seconds....
- roughly one centimetreCentimetreA centimetre is a unit of length in the metric system, equal to one hundredth of a metre, which is the SI base unit of length. Centi is the SI prefix for a factor of . Hence a centimetre can be written as or — meaning or respectively...
per minuteMinuteA minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
(to within 1 part in 400). - 5.987 km/h
- 6.548 inchInchAn inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
per secondSecondThe second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock.... - roughly three eighths of an inch per minute
- 3.720 mph
- the speed of the tip of an hour hand on a clock, measuring 1.143 metres (3.751 ft) in length
- the speed of the tip of a minute hand on a clock, measuring 9.528 centimetres (3.751 inches) in length
- the speed of the tip of a second hand on a clock, measuring 1.588 mm ( of an inch) in length
Thus:
- a car travelling at 60 km/h (37 mph) has a speed of 1.00 furlongs per fortnight;
- an airplane cruising at 420 knots or 216.2 m/s (i.e., typical 0.8 Mach cruise) is travelling at 1.300 furlongs per fortnight;
- the speed of lightSpeed of lightThe speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
in vacuum is approximately 1.803 furlongs per fortnight, or rather 1.803 terafurlongs per fortnight; - fingernails grow approximately 3 mm per month or 6.96 microfurlongs per fortnight (6.96 furlongs per fortnight);
- human hair grows between 2 and 4.5 times as fast;
- a garden snailHelix aspersaHelix aspersa, known by the common name garden snail, is a species of land snail, a pulmonate gastropod that is one of the best-known of all terrestrial molluscs. The species has been placed in the genus Helix, in all sources between 1774 and 1988 and in most sources until recently...
has a top speed of about 78 furlongs per fortnight.