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The definition, agreement and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. Disparate systems of measurement used to be very common. Now there is a global standard, the International System (SI) of units informally known as the Metric System. The SI has been or is in the process of being adopted in most major countries of the world with the exception of the United States of America. In classical physics and engineering, measurement generally refers to the process of estimating or determining the ratio of a magnitude of a quantitative property or relation to a unit of the same type of quantitative property or relation. ...
The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. ...
The International System of Units (symbol: SI) (for the French phrase Syst me International dUnit s) is the most widely used system of units. ...
Speedometer gauges on a car showing the speed of the vehicle in miles and kilometres per hour Metrication, or metrification, is the process of converting from the various other systems of units used throughout the world to the metric or SI (Système International) system. ...
Standards are very important. Each unit is a set size. A distance or length or volume or mass or span of time being measured is described as a certain number of these units. Sometimes more than one unit is used to get better accuracy, or a smaller unit is used - so one can say "one metre, 95 centimetres" or just "195 centimetres". The word standard has several meanings: Classically, standard referred to a flag or banner; especially, a national or other ensign carried into battle; thus standard bearer indicates the one who bears, or carries, the standard. ...
In science, engineering, industry and statistics, accuracy is the degree of conformity of a measured or calculated quantity to its actual, nominal, or some other reference, value. ...
Just to underline the importance of agreed units, the NASA Mars Polar Lander in December 1999 crashed on the planet Mars instead of staying in orbit, due to miscommunications about the value of forces: different people used different assumptions about the unit of measurement (newton versus pound force). Enormous amounts of effort, time and money were wasted. NASA Logo Listen to this article · (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ...
Conceptual drawing The Mars Polar Lander was part of the Mars Surveyor 98 program, which consisted of two spacecraft launched separately, the Mars Climate Orbiter (formerly the Mars Surveyor 98 Orbiter) and the Mars Polar Lander (formerly the Mars Surveyor 98 Lander). ...
1999 is a common year starting on Friday Anno Domini (or the Current Era), and was designated the International Year of Older Persons by the United Nations. ...
A planet in common parlance is a large object in orbit around a star that is not a star itself. ...
Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...
In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ...
In physics, the newton (symbol: N) is the SI unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics. ...
The pound-force is a non-SI unit of force or weight (properly abbreviated lbf or lbf). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9. ...
In physics and metrology, units are standards for measurement of physical quantities that need clear definitions to be useful. Reproducibility of experimental results is central to the scientific method. To facilitate this we need standards, and to get convenient measures of the standards we need a system of units. Scientific systems of units are a formalization of the concept of weights and measures, initially developed for commercial purposes. Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. ...
Metrology is the science and process of ensuring that a measurement meets specified degrees of both accuracy and precision. ...
In classical physics and engineering, measurement generally refers to the process of estimating or determining the ratio of a magnitude of a quantitative property or relation to a unit of the same type of quantitative property or relation. ...
A physical quantity is either a quantity within physics that can be measured (e. ...
Reproducibility is one of the main principles of the scientific method. ...
The characterization phase can require extended and extensive study, even centuries. ...
The word standard has several meanings: Classically, standard referred to a flag or banner; especially, a national or other ensign carried into battle; thus standard bearer indicates the one who bears, or carries, the standard. ...
Weights and measures is a term used by legal authorities in English speaking countries such as the United Kingdom for a function related to units of measurement in trade. ...
Different systems of units are based on different choices of a set of fundamental units. The most widely used system of units is the International System of Units, or SI. There are seven SI base units. All other SI units can be derived from these base units. In the language of measurement, quantities are quantifiable aspects of the world, such as time, distance, velocity, mass, and weight, and units measure them. ...
The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. ...
The SI system of units defines seven SI base units: fundamental physical units defined by an operational definition. ...
SI derived units are part of the SI system of measurement units and are derived from the seven SI base units. ...
Units as dimensions Any value of a physical quantity is expressed as a comparison to a unit of that quantity. For example, the value of a physical quantity Q is written as the product of a unit [Q] and a numerical factor: ![Q = n times [Q] = n [Q]](http://en.wikipedia.org/math/47d0531b33d4ac705a21a8e2113283f0.png) The multiplication sign is usually left out, just as it is left out between variables in scientific notation of formulas. In formulas the unit [Q] can be treated as if it was a kind of physical dimension: see dimensional analysis for more on this treatment. Dimension (from Latin measured out) is, in essence, the number of degrees of freedom available for movement in a space. ...
Dimensional analysis is a conceptual tool often applied in physics, chemistry, and engineering to understand physical situations involving a mix of different kinds of physical quantities. ...
A distinction should be made between units and standards. A unit is fixed by its definition, and is independent of physical conditions such as temperature. By contrast, a standard is a physical realization of a unit, and realizes that unit only under certain physical conditions. For example, the metre is a unit, while a metal bar is a standard. One metre is the same length regardless of temperature, but a metal bar will be one metre long only at a certain temperature.
Base and derived units For most quantities a unit is absolutely necessary to communicate values of that physical quantity. For example, conveying to someone a particular length without using some sort of unit is impossible, because a length cannot be described without a reference used to make sense of the value given.
But not all quantities require a unit of their own. Using physical laws, units of quantities can be expressed as combinations of units of other quantities. Thus only a small set of units is required. These units are taken as the base units. Other units are derived units. Derived units are a matter of convenience, as they can be expressed in terms of basic units. Which units are considered base units is a matter of choice.
The base units of SI are actually not the smallest set. Smaller sets have been defined. There are sets in which the electric and magnetic field have the same unit. This is based on physical laws that show that electric and magnetic field are actually different manifestations of the same phenomenon. In some fields of science such systems of units are highly favored over the SI system. The SI system of units defines seven SI base units: fundamental physical units defined by an operational definition. ...
In physics, an electric field or E-field is an effect produced by an electric charge that exerts a force on charged objects in its vicinity. ...
Current flowing through a wire produces a magnetic field (M) around the wire. ...
Conversion of units Conversion of units involves comparison of different standard physical values, either of a single physical quantity or of a physical quantity and a combination of other physical quantities. This article lists conversion factors between a number of units of measurement. ...
Calculations with units Guidelines: - Treat units like variables. Only add like terms. When a unit is divided by itself, the division yields a unitless one. When two different units are multiplied, the result is a new unit, referred to by the combination of the units. For instance, in SI, the unit of speed is meters per second (m/s). See dimensional analysis. A unit can be multiplied by itself, creating a unit with an exponent (ex: m2).
- Some units have special names, however these should be treated like their equivalents. For example, one newton (N) is equivalent to one kg m/s2. This creates the possiblity for units with multiple designations, for example: the unit for surface tension can be referred to as either N/m (newtons per meter) or kg/s2 (kilograms per second squared).
- Don't let definitions like density is mass per unit volume obscure your understanding of units. It sounds as if it says:
- D = m/m3 (mass divided by the unit of volume) (WRONG)
This is not true. The correct statement is that density is mass divided by volume: Dimensional analysis is a conceptual tool often applied in physics, chemistry, and engineering to understand physical situations involving a mix of different kinds of physical quantities. ...
In physics, surface tension is an effect within the surface layer of a liquid that causes the layer to behave as an elastic sheet. ...
- D = m/V (mass divided by volume, both variables)
Expressing a physical value in terms of another unit Starting with: ![Q = n_i times [Q]_i](http://en.wikipedia.org/math/31945b0e67d38bf2b241928d2d598c30.png) just replace the original unit [Q]_i with its meaning in terms of the desired unit [Q]f, e.g. if [Q]i = cij * [Q]f, then: ![Q = n_i times c_ij times [Q]_f](http://en.wikipedia.org/math/11a0baccc015e1907aa4ffa8034d73de.png) Now ni and cij are both numerical values, so just calculate their product.
Or, which is just mathematically the same thing, multiply Q by unity, the product is still Q:
![Q = n_i times [Q]_i times ( c_ij times [Q]_f/[Q]_i )](http://en.wikipedia.org/math/fc2275e288eb66ef6a7ba1f157a16f25.png) For example, you have an expression for a physical value Q involving the unit feet per second ([Q]i) and you want it in terms of the unit miles per hour ([Q]f): - Find facts relating the original unit to the desired unit:
- 1 mile = 5280 feet and 1 hour = 3600 seconds
- Next use the above equations to construct a fraction that has a value of unity and that contains units such that, when it is multiplied with the original physical value, will cancel the original units:
- 1 = (1 mile) / (5280 feet) and 1 = (3600 seconds) / (1 hour)
- Last, multiply the original expression of the physical value by the fraction, called a conversion factor, to obtain the same physical value expressed in terms of a different unit. Note: since the conversion factors have a numerical value of unity, multiplying any physical value by them will not change that value.
This article lists conversion factors between a number of units of measurement. ...
Systems of measurement
The metric system Metric systems of units have evolved since the adoption of the first well-defined system in France in 1791. During this evolution the use of these systems spread throughout the world, first to the non-English-speaking countries, and more recently to the English speaking countries. The International System of Units (symbol: SI) (for the French phrase Syst me International dUnit s) is the most widely used system of units. ...
1791 was a common year starting on Saturday (see link for calendar). ...
In the early metric system there were two fundamental or base units, the metre and the kilogram, for length and mass. The other units of length and mass, and all units of area, volume, and compound units such as density were derived from these two fundamental units. The metre, or meter, is the basic unit of length in the International System of Units (SI: Système International dUnités). ...
The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ...
Multiples and submultiples of metric units are related by powers of ten; the names for these are formed with SI prefixes. This relationship is compatible with the decimal system of numbers and it contributes greatly to the convenience of metric units. An SI prefix is a prefix that can be applied to an SI unit to form a decimal multiple or submultiple. ...
The present metric system is the Système international d'unités (SI, International System of Units). It is also based on the metre, kilogram and second as well as additional base units for temperature, electric current, luminous intensity, and amount of substance. The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. ...
The metre, or meter, is the basic unit of length in the International System of Units (SI: Système International dUnités). ...
The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ...
The second (symbol s) is a unit for time, and one of seven SI base units. ...
Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ...
In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ...
Luminous intensity is a measure of the energy emitted by a light source in a particular direction. ...
The mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry. ...
The SI includes two classes of units which are defined and agreed internationally. The first of these classes are the seven SI base units for length, mass, time, temperature, electric current, luminous intensity and amount of substance. The second of these are the SI derived units. These derived units are defined in terms of the seven base units. All other quantities (e.g. work, force, power) are expressed in terms of SI derived units. The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. ...
The SI system of units defines seven SI base units: fundamental physical units defined by an operational definition. ...
SI derived units are part of the SI system of measurement units and are derived from the seven SI base units. ...
SI derived units are part of the SI system of measurement units and are derived from the seven SI base units. ...
Imperial and US Customary units Both the Imperial units and US customary units derive from earlier English units. Imperial units were mostly used in the British Commonwealth and the former British Empire. They are still used to some extent but have now been mostly replaced by the metric system. US customary units are the main system of measurement in the United States however some steps towards metrication have been made. The metric system is prefered in certain fields such as science, medicine and technology. This article is about post-1824 Imperial units, please see also English unit, U.S. customary unit or Avoirdupois. ...
The U.S. customary units (more commonly known in the US as English units or standard units) are the non-metric units of measurement that are presently used in the United States, in some cases alongside the metric system of units. ...
There is no one system of English units. ...
Flag of the Commonwealth of Nations The Commonwealth of Nations is a voluntary association of independent sovereign states, most of which were once governed by the United Kingdom and are its former colonies. ...
The British Empire in 1897, marked in pink, the traditional colour for Imperial British dominions on maps The British Empire was the worlds first global power, a product of the European Age of Exploration that began with the global maritime empires of Portugal and Spain in the late 1400s. ...
The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. ...
Speedometer gauges on a car showing the speed of the vehicle in miles and kilometres per hour Metrication, or metrification, is the process of converting from the various other systems of units used throughout the world to the metric or SI (Système International) system. ...
// What is science? There are different theories of what science is. ...
Medicine on the Web NLM (National Library of Medicine, contains resources for patients and healthcare professionals) Virtual Hospital (digital health sciences library by the University of Iowa) Online Medical Dictionary Collection of links to free medical resources Categories: Medicine | Health ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
These two systems are closely related. Units of length and area (the inch, foot, yard, mile, acre, etc.) are identicle except for surveying purposes. Units of mass and weight differ for units larger than a pound (lb.). The Imperial system uses a stone of 14 lb., a long hundredweight of 112 lb. and a long ton of 2240 lb. The stone is not used in the US and the hundredweights and tons are short being 100 lb. and 2000 lb. respectively. Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
This article is about the unit of measure known as the yard. ...
A mile is any of several units of distance, or, in physics terminology, of length. ...
An acre is an English unit of area. ...
Officially the pound is the name for at least three different units of mass: The pound (avoirdupois). ...
Hundred weight or hundredweight is a unit of measurement for mass in both the system of measurement used in the United Kingdom and Ireland (and previously throughout the British Commonwealth), and in the system used in the United States. ...
The word ton or tonne is derived from the Old English tunne, and ultimately from the Old French tonne, and referred originally to a large cask with a capacity of 252 wine gallons, which holds approximately 2100 pounds of water. ...
Where these systems most notably differ is in their respective units of volume. A US fluid ounces (fl. oz.) is slightly larger than it's Imperial equivalent (the former being approximately 29.6 ml and the latter 28.4 ml). However, as there are 16 US fl. oz. to a US pint as opposed to the 20 Imperial fl. oz. per Imperial pint these pints are quite different in volume. The same is true of quarts, gallons, etc. Six US gallons are a little less than five Imperial gallons. A fluid ounce is a unit of volume in both the Imperial system of units and the U.S. customary units system. ...
The millilitre (spelled milliliter in American English and German) is a metric unit of volume that is equal to one thousandth of a litre. ...
The pint is a unit of volume. ...
A quart is a unit of measurement for volume. ...
The gallon (abbr. ...
Natural units The above systems of units are based on arbitrary unit values, formalised as standards. Some unit values occur naturally in Science. Systems of units based on these are called Natural units. The following are examples of these system of natural units. In physics, Planck units are physical units of measurement originally proposed by Max Planck. ...
In physics, Planck units are physical units of measurement originally proposed by Max Planck. ...
In physics, especially in the general theory of relativity, geometrized units or sometimes geometric units, is a physical unit system in which all physical quantities are expressed in the unit of length: meter. ...
Non-standard units Non-standard measurement units sometimes found in books etc include:- - A ton of TNT, and its multiples the kiloton and the megaton and the gigaton. Often used in stating the power of very energetic events such as explosions and volcanic events and earthquakes and asteroid impacts. A gram of TNT as a unit of energy has been defined as 1000 thermochemical calories = roughly 4184 joules.
- The Hiroshima atom bomb. Its force is often used in the public media and popular books as a unit of energy. (Its yield was roughly 13 kilotons.)
- The weight of an elephant. It is often used as a unit of weight in popular books about very big animals such as dinosaurs. This unit needs to be defined, as the real weight of elephants varies much with age and sex and species.
Trinitrotoluene (TNT, or Trotyl) is a pale yellow crystalline aromatic hydrocarbon compound that melts at 354 K (178 °F, 81 °C). ...
A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ...
A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ...
A gigaton (or gigatonne) is a Metric Unit of mass, equal to 1,000,000,000 (1 billion) Metric tons, 1,000,000,000,000 (1 trillion) kilograms, or 1 quadrillion grams. ...
This article is about volcanoes in geology. ...
Global earthquake epicenters, 1963–1998. ...
An asteroid is a small, solid object in our Solar System, orbiting the Sun. ...
The gram or gramme, symbol g, is a unit of mass, and is defined in the SI system of units as one one-thousandth of a kilogram (i. ...
A calorie refers to a unit of energy. ...
The joule (symbol J, also called newton metre, or coulomb volt) is the SI unit of energy and work. ...
Main keep of Hiroshima Castle The city of Hiroshima (広島市; -shi) is the capital of Hiroshima Prefecture, and the largest city in the Chugoku region of western Honshu, the largest of Japans islands. ...
The mushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 18 km (60,000 feet) above the epicenter. ...
The public media is the sum of the public mass distributors of news and entertainment: the newspapers, and television and radio broadcasting, and suchlike. ...
[1]#redirect Book ...
Genera and Species Loxodonta Loxodonta cyclotis Loxodonta africana Elephas Elephas maximus Elephas recki (extinct) Stegodon (extinct) Deinotherium (extinct) Mammuthus (extinct) Elephantidae (the elephants) is a family of animals, the only family in the order Proboscidea that still exists today. ...
Orders Saurischia Sauropodomorpha Theropoda Ornithischia Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. ...
Historical systems of measurement - Main article: Historical weights and measures
Prior to the global adoption of the metric system many different systems of measurement had been in use. Many of these were related to some extent or other. Often they were based on the dimensions of the human body. This article needs to be cleaned up to conform to a higher standard of quality. ...
Other units
Units of currency A unit of measurement that applies to money is called a unit of account. This is normally a currency issued by a country or a fraction thereof; for instance, the US dollar and US cent (1/100 of a dollar), or the Euro and Eurocent. Money Money is any marketable good or token used by a society as a store of value, a medium of exchange, and a unit of account. ...
In economics, the unit of account is a unit of measurement of market value. ...
A country, a land, is a geographical area that connotes an independent political entity, with its own government, administration, laws, often a constitution, police, military, tax rules, and population, who are one anothers countrymen. ...
The United States dollar is the official currency of the United States. ...
The euro (€; ISO 4217 code EUR) is the currency of twelve European Union member states: Austria, Belgium, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, and Spain, collectively known as Eurozone. ...
The euro (€; ISO 4217 code EUR) is the currency of twelve of the twenty-five nations that form the European Union (and four outside it, as well as Montenegro and Kosovo), which form the Economic and Monetary Union (EMU). ...
Units used in science, medicine and engineering Science, medicine and engineering use larger and smaller units of measurement than these, and talk about them more exactly. For instance, the difference between mass and weight matters a lot more in these fields. In these fields, the judicious selection of the units of measure can actually aid the researchers in both framing and solving the problem. // What is science? There are different theories of what science is. ...
Medicine on the Web NLM (National Library of Medicine, contains resources for patients and healthcare professionals) Virtual Hospital (digital health sciences library by the University of Iowa) Online Medical Dictionary Collection of links to free medical resources Categories: Medicine | Health ...
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Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ...
Weight is the interaction of matter with a gravitational field. ...
This topic differs from units of measurement, which see. ...
Problem solving forms part of thinking. ...
History Units of measurement were among the earliest tools invented by humans. Primitive societies needed rudimentary measures for many tasks: constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials. (See also List of types of clothing and Clothing terminology) Humans nearly universally wear articles of clothing (also known as dress, garments, or attire) on the body. ...
Barter is a simple form of trade where goods or services are exchanged for a certain amount of other goods or services, i. ...
material is the substance or matter from which something is or can be made, or also items needed for doing or creating something. ...
The earliest known uniform systems of weights and measures seem to have all been created sometime in the 4th and 3rd millennia BC among the ancient peoples of Mesopotamia, Egypt and the Indus Valley, and perhaps also Elam in Persia as well. The most astounding of these ancient systems was perhaps that of the Indus Valley Civilization (ca. 2600 BC). The Indus Valley peoples achieved great accuracy in measuring length, mass, and time. Their measurements were extremely precise. Their smallest division, which is marked on an ivory scale found in Lothal, was approximately 1.704mm, the smallest division ever recorded on a scale of the Bronze Age. The decimal system was used. Harappan engineers followed the decimal division of measurement for all practical purposes, including the measurement of mass as revealed by their hexahedron weights. Weights were based on units of 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, and 500, with each unit weighing approximately 28 grams, similar to the English ounce or Greek uncia, and smaller objects were weighed in similar ratios with the units of 0.871. (5th millennium BC – 4th millennium BC – 3rd millennium BC - other millennia) // Events City of Ur in Mesopotamia (40th century BC). ...
(4th millennium BC – 3rd millennium BC – 2nd millennium BC – other millennia) Events Syria: Foundation of the city of Mari (29th century BC ) Iraq: Creation of the Kingdom of Elam Germination of the Bristlecone pine tree Methuselah about 2700 BC, the oldest known tree still living now Dynasty of Lagash in...
Mesopotamia (Greek: Μεσοποταμία, translated from Old Persian Miyanrudan the Land between the Rivers; Aramaic name being Beth-Nahrain House of Two Rivers) is a region of Southwest Asia. ...
The Indus (सिन्धु नदी) (known as Sindhu in ancient times) is the principal river of Pakistan. ...
Map showing the area of the Elamite Empire (in red) and the neighboring areas. ...
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The Indus Valley Civilization existed along the Indus River in present-day Pakistan. ...
(Redirected from 2600 BC) (27th century BC - 26th century BC - 25th century BC - other centuries) (4th millennium BC - 3rd millennium BC - 2nd millennium BC) Events 2900 - 2334 BC – Mesopotamian wars of the Early Dynastic period. ...
Archeological site Lothal harbour Lothal was a city of the Indus Valley Civilization situated 450 miles South-East of Mohenjo Daro. ...
The Bronze Age is a period in a civilizations development when the most advanced metalworking has developed the techniques of smelting copper from natural outcroppings and alloys it to cast bronze. ...
Decimal, or less commonly, denary, usually refers to the base 10 numeral system. ...
Harappa is a city in Punjab, northeast Pakistan, located beside a former course of the Ravi River; about 35km southwest of Sahiwal. ...
Other systems were based on the use of parts of the body and the natural surroundings as measuring instruments. Early Babylonian and Egyptian records and the Bible indicate that length was first measured with the forearm, hand, or finger and that time was measured by the periods of the sun, moon, and other heavenly bodies. When it was necessary to compare the capacities of containers such as gourds or clay or metal vessels, they were filled with plant seeds which were then counted to measure the volumes. When means for weighing were invented, seeds and stones served as standards. For instance, the carat, still used as a unit for gems, was derived from the carob seed. Babylonia was an ancient state in Mesopotamia (in modern Iraq), combining the territories of Sumer and Akkad. ...
The holy Jewish scripture: The Torah. ...
A gourd is a hollow, dried shell of a fruit in the Cucurbitaceae family of plants. ...
Clay is a generic term for an aggregate of hydrous silicate particles less than 4 μm (micrometres) in diameter. ...
Volume, also called capacity, is a quantification of how much space an object occupies. ...
Meanings of Carat or Karat: Carat is a unit of mass for gems. ...
Carob trees near Mehmetcik, Northern Cyprus Carob tree (Ceratonia siliqua) is a species native to the Mediterranean region, cultivated for its edible seed pods. ...
Our present knowledge of early weights and measures comes from many sources. Archaeologists have recovered some rather early standards and preserved in museums. The comparison of the dimensions of buildings with the descriptions of contemporary writers is another source of information. An interesting example of this is the comparison of the dimensions of the Greek Parthenon with the description given by Plutarch from which a fairly accurate idea of the size of the Attic foot is obtained. In some cases, we have only plausible theories and we must sometimes select the interpretation to be given to the evidence. Archaeology or sometimes in American English archeology (from the Greek words αρχαίος = ancient and λόγος = word/speech) is the study of human cultures through the recovery, documentation and analysis of material remains, including architecture, artefacts, biofacts, human remains, and landscapes. ...
The Parthenon seen from the hill of the Pnyx to the west The Parthenon (Greek: ΠαÏθενών) is the most famous surviving building of Ancient Greece and one of the most famous buildings in the world. ...
Mestrius Plutarch (cz. ...
For example, does the fact that the length of the double-cubit of early Babylonia was equal (within two parts per thousand) to the length of the seconds pendulum at Babylon suggest a scientific knowledge of the pendulum at a very early date, or do we merely have a curious coincidence? By studying the evidence given by all available sources, and by correlating the relevant facts, we obtain some idea of the origin and development of the units. We find that they have changed more or less gradually with the passing of time in a complex manner because of a great variety of modifying influences. We find the units modified and grouped into measurement systems: the Babylonian system, the Egyptian system, the Phileterian system of the Ptolemaic age, the Olympic system of Greece, the Roman system, and the British system, to mention only a few. Simple Gravity Pendulum assumues no air resistance and no friction of/at the nail/screw. ...
Ptolemy, one of Alexander the Greats generals, was appointed satrap of Egypt after Alexanders death in 323 BC. In 305 BC he declared himself King Ptolemy I, later known as Soter (saviour). ...
See Historical weights and measures for a detailed listing of actual units. The origin and development of units of measurement has been investigated in considerable detail and a number of books have been written on the subject. It is only possible to give here, somewhat sketchily, the story about a few units. This article needs to be cleaned up to conform to a higher standard of quality. ...
Units of length The Indus Valley units of length referred to above and the Mesopotamian cubit were both used in the 3rd millennium BC and are the earliest known units used by ancient peoples to measure length. The Indus (सिन्धु नदी) (known as Sindhu in ancient times) is the principal river of Pakistan. ...
Cubit is the name for any one of many units of measure used by various ancient peoples, based on the distance between the tip of the middle finger and the elbow on an average person or a similar forearm-based measurement. ...
(4th millennium BC – 3rd millennium BC – 2nd millennium BC – other millennia) Events Syria: Foundation of the city of Mari (29th century BC ) Iraq: Creation of the Kingdom of Elam Germination of the Bristlecone pine tree Methuselah about 2700 BC, the oldest known tree still living now Dynasty of Lagash in...
There were several cubits of different magnitudes that were used. The common cubit was the length of the forearm from the elbow to the tip of the middle finger. It was divided into the span of the hand (one-half cubit), the palm or width of the hand (one sixth), and the digit or width of a finger (one twenty-fourth). The Royal or Sacred Cubit, which was 7 palms or 28 digits long, was used in constructing buildings and monuments and in surveying. The inch, foot (length), and yard evolved from these units through a complicated transformation not yet fully understood. Some believe they evolved from cubic measures; others believe they were simple proportions or multiples of the cubit. In any case, the Greeks and Romans inherited the foot from the Egyptians. The Roman foot was divided into both 12 unciae (inches) and 16 digits. The Romans also introduced the mile of 1000 paces or double steps, the pace being equal to five Roman feet. The Roman mile of 5000 feet was introduced into England during the occupation. Queen Elizabeth I (reigned from 1558 to 1603) changed, by statute, the mile to 5280 feet or 8 furlongs, a furlong being 40 rods of 5.5 yards each. Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ...
This article is about a foot as a unit of length. ...
This article is about the unit of measure known as the yard. ...
A mile is any of several units of distance, or, in physics terminology, of length. ...
Elizabeth I (7 September 1533 – 24 March 1603 ) was Queen of England and Queen of Ireland from 17 November 1558 until her death. ...
Events January 7 - French troops led by Francis, Duke of Guise take Calais, the last continental possession of England July 13 - Battle of Gravelines: In France, Spanish forces led by Count Lamoral of Egmont defeat the French forces of Marshal Paul des Thermes at Gravelines. ...
King James I of England/VII of Scotland, the first monarch to rule the Kingdoms of England and Scotland at the same time Events March 24 - Elizabeth I of England dies and is succeeded by her cousin King James VI of Scotland, uniting the crowns of Scotland and England April...
The 5 furlong (1006 m) post on Epsom Downs A furlong is a measure of distance within Imperial units and U.S. customary units. ...
A rod is a unit of length, equal to 5. ...
The introduction of the yard as a unit of length came later, but its origin is not definitely known. Some believe the origin was the double cubit, others believe that it originated from cubic measure. Whatever its origin, the early yard was divided by the binary method into 2, 4, 8, and 16 parts called the half-yard, span, finger, and nail. The association of the yard with the "gird" or circumference of a person's waist or with the distance from the tip of the nose to the end of the thumb of King Henry I (reigned 1100 - 1135) are probably standardizing actions, since several yards were in use in Britain. Henry I (c. ...
For alternate uses, see Number 1100. ...
Events January - Byland Abbey founded Stephen of Blois succeeds King Henry I. Empress Maud, daughter of Henry I and widow of Henry V opposed Stephen and claims the throne as her own Owain Gwynedd of Wales defeats the Normans at Crug Mawr. ...
Typographical units The point, which is a unit for measuring print type, is recent. It originated with Pierre Simon Fournier in 1737. It was modified and developed by the Didot brothers, Francois Ambroise and Pierre Francois, in 1755. The point was first used in the United States in 1878 by a Chicago type foundry (Marder, Luse, and Company). Since 1886, a point has been exactly 0.3514598 millimetres, or 1/72.27 inch. The word point can refer to: a location in physical space a unit of angular measurement; see navigation point is a typographic unit of measure in typography equal inch or sometimes approximated as inch; on computer displays it should be equal to point in typography if the correct display resolution...
Units of mass The grain was the earliest unit of mass and is the smallest unit in the apothecary, avoirdupois, Tower, and troy systems. The early unit was a grain of wheat or barleycorn used to weigh the precious metals silver and gold. Larger units preserved in stone standards were developed that were used as both units of mass and of monetary currency. The pound was derived from the mina used by ancient civilizations. A smaller unit was the shekel, and a larger unit was the talent. The magnitude of these units varied from place to place. The Babylonians and Sumerians had a system in which there were 60 shekels in a mina and 60 minas in a talent. The Roman talent consisted of 100 libra (pound) which were smaller in magnitude than the mina. The troy pound used in England and the United States for monetary purposes, like the Roman pound, was divided into 12 ounces, but the Roman uncia (ounce) was smaller. The carat is a unit for measuring gemstones that had its origin in the carob seed, which later was standardized at 1/144 ounce and then 0.2 gram. The apothecaries system of mass is an obsolete system formerly used by apothecaries (now called pharmacists or chemists) in English-speaking countries. ...
The avoirdupois system is a system of weights defining terms such as pound and ounce. ...
Troy weight is a system of units of mass customarily used for precious metals and gemstones. ...
A talent is an ancient unit of mass. ...
Goods of commerce were originally traded by number or volume. When weighing of goods began, units of mass based on a volume of grain or water were developed. For example, the talent in some places was approximately equal to the mass of one cubic foot of water. Was this a coincidence or by design? The diverse magnitudes of units having the same name, which still appear today in our dry and liquid measures, could have arisen from the various commodities traded. The larger avoirdupois pound for goods of commerce might have been based on volume of water which has a higher bulk density than grain. For example, the Egyptian hon was a volume unit about 11 per cent larger than a cubic palm and corresponded to one mina of water. It was almost identical in volume to the present U.S. pint.
The stone, quarter, hundredweight, and ton were larger units of mass used in Britain. Today only the stone continues in customary use for measuring personal body weight. The present stone is 14 pounds, but an earlier unit appears to have been 16 pounds. The other units were multiples of 2, 8, and 160 times the stone, or 28, 112, and 2240 pounds, respectively. The hundredweight was approximately equal to two talents. The ton of 2240 pounds is called the "long ton". The "short ton" is equal to 2000 pounds.
Units of time and angle We can trace the division of the circle into 360 degrees and the day into hours, minutes, and seconds to the Babylonians who had a sexagesimal system of numbers. The 360 degrees may have been related to a year of 360 days.
See also History and current usage of the metric system in the United States. ...
The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. ...
In physics, Planck units are physical units of measurement originally proposed by Max Planck. ...
This article is about post-1824 Imperial units, please see also English unit, U.S. customary unit or Avoirdupois. ...
The U.S. customary units (more commonly known in the US as English units or standard units) are the non-metric units of measurement that are presently used in the United States, in some cases alongside the metric system of units. ...
Strange and whimsical units are sometimes used by scientists, especially physicists and mathematicians, and other technically-minded people such as engineers and programmers, as bits of dry humor combined with putative practical convenience. ...
This article lists conversion factors between a number of units of measurement. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
It has been suggested that this article or section be merged with Units of measurement. ...
International Standard ISO 31 (Quantities and units, International Organization for Standardization, 1992) is the most widely respected style guide for the use of units of measurement, and formulas involving them, in scientific and educational documents worldwide. ...
units is a Unix computer program for conversion of units of weights and measures. ...
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References Appendix B of NIST Handbook 44, 2002 Edition |
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