Explore topic-wise fullforms in Measurement Unit

The metre (Commonwealth spelling) or meter (American spelling; see spelling differences) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in the International System of Units (SI). The SI unit symbol is m.

The metre is currently defined as the length of the path travelled by light in a vacuum in 1/299 792 458 of a second.

The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately 40000 km. In 1799, the metre was redefined in terms of a prototype metre bar (the actual bar used was changed in 1889). In 1960, the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and modified slightly in 2002 to clarify that the metre is a measure of proper length.

Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller countries, most of which are UK or US territories, or have close historical ties with the UK or US.

INFO: Full form for MOA is Minutes of Angle in Measurement Unit category
MOA also has other full forms in other categories mentioned below.

INFO: Full form for MOA is Months of Age in Measurement Unit category
MOA also has other full forms in other categories mentioned below.

INFO: Full form for OCI is One Chance In in Measurement Unit category
OCI also has other full forms in other categories mentioned below.

INFO: Full form for UMT is Unit of Medical Time in Measurement Unit category
UMT also has other full forms in other categories mentioned below.

INFO: Full form for ALU is Average Labor Unit in Measurement Unit category
ALU also has other full forms in other categories mentioned below.

The following are examples of orders of magnitude for different lengths.

INFO: Full form for VA is Volt Amperes in Measurement Unit category
VA also has other full forms in other categories mentioned below.

INFO: Full form for GtC is Gigatons of Carbon in Measurement Unit category
GtC also has other full forms in other categories mentioned below.

INFO: Full form for CPI is Counts Per Inch in Measurement Unit category
CPI also has other full forms in other categories mentioned below.

INFO: Full form for TRS is Temperature Ratio Scale in Measurement Unit category
TRS also has other full forms in other categories mentioned below.

INFO: Full form for TCW is Total Carat Weight in Measurement Unit category
TCW also has other full forms in other categories mentioned below.

A peck is an imperial and United States customary unit of dry volume, equivalent to 2 dry gallons or 8 dry quarts or 16 dry pints. An imperial peck is equivalent to 9.09 liters and a US customary peck is equivalent to 8.81 liters. Two pecks make a kenning (obsolete), and four pecks make a bushel. Although the peck is no longer widely used, some produce, such as apples, are still often sold by the peck in the USA (although it is obsolete in the UK, found only in the old nursery rhyme "Peter Piper" and in the Bible - e.g., Matthew 5:15 in some older translations).

The second (symbol: s, abbreviation: sec) is the base unit of time in the International System of Units (SI) (French: Système International d’unités), commonly understood and historically defined as 1⁄86400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each. Analog clocks and watches often have sixty tick marks on their faces, representing seconds (and minutes), and a "second hand" to mark the passage of time in seconds. Digital clocks and watches often have a two-digit seconds counter. The second is also part of several other units of measurement like meters per second for speed, meters per second per second for acceleration, and cycles per second for frequency.

Although the historical definition of the unit was based on this division of the Earth's rotation cycle, the formal definition in the International System of Units (SI) is a much steadier timekeeper:

The second is defined as being equal to the time duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental unperturbed ground-state of the caesium-133 atom.

Because the Earth's rotation varies and is also slowing ever so slightly, a leap second is added at irregular intervals to clock time to keep clocks in sync with Earth's rotation.

Multiples of seconds are usually counted in hours and minutes. Fractions of a second are usually counted in tenths or hundredths. In scientific work, small fractions of a second are counted in milliseconds (thousandths), microseconds (millionths), nanoseconds (billionths), and sometimes smaller units of a second. An everyday experience with small fractions of a second is a 1-gigahertz microprocessor which has a cycle time of 1 nanosecond. Camera shutter speeds are often expressed in fractions of a second, such as 1⁄30 second or 1⁄1000 second.

Sexagesimal divisions of the day from a calendar based on astronomical observation have existed since the third millennium BC, though they were not seconds as we know them today. Small divisions of time could not be measured back then, so such divisions were mathematically derived. The first timekeepers that could count seconds accurately were pendulum clocks invented in the 17th century. Starting in the 1950s, atomic clocks became better timekeepers than Earth's rotation, and they continue to set the standard today.

INFO: Full form for DQ is Dimension Quantifier in Measurement Unit category
DQ also has other full forms in other categories mentioned below.

INFO: Full form for PTB is Pounds Per Thousand Barrels in Measurement Unit category
PTB also has other full forms in other categories mentioned below.