トン

Ton — Grokipedia Fact-checked by Grok 3 months ago Ton Ara Eve Leo Sal 1x The ton is a unit of mass or weight primarily used in the avoirdupois system, with variations including the short ton (2,000 pounds or approximately 907.18 kilograms) common in the United States, the long ton (2,240 pounds or approximately 1,016.05 kilograms) historically used in the United Kingdom and some Commonwealth countries, and the metric ton or tonne (1,000 kilograms or approximately 2,204.62 pounds) adopted internationally under the metric system . [1] [2] The term originates from the Old English "tunne," referring to a large cask or barrel for wine or ale, whose capacity and typical filled weight established the unit's foundational value in medieval trade and shipping. [3] Historically, the ton evolved from ancient volumetric measures tied to cargo like barrels of goods, with the short and long tons emerging in the 19th century to standardize imperial weights for commerce, coal, and shipping, while the metric ton was formalized in 1875 via the Metric Convention to align with the kilogram for global consistency. [1] These distinctions persist due to lingering imperial influences, leading to potential confusion in international trade; for instance, one short ton is about 0.907 metric tons, while one long ton is roughly 1.016 metric tons. [4] Beyond mass, "ton" also denotes derived units like the ton of refrigeration (capacity to freeze one short ton of water in 24 hours) in engineering and the displacement ton in naval architecture for ship volume. [3] In modern usage, the metric ton dominates scientific, industrial, and global contexts, reflecting the widespread adoption of the International System of Units (SI). [2] Introduction Definition A ton is a unit of measurement historically employed to quantify large quantities of mass or volume , with its exact value varying by regional standards and context. In terms of mass , it typically represents between 2,000 and 2,240 pounds (approximately 907 to 1,016 kilograms), serving as a non-metric imperial unit primarily in trade, shipping, and industry. [5] For volume , particularly in maritime freight, a ton often denotes 40 to 100 cubic feet (approximately 1.13 to 2.83 cubic meters), though specific applications like the measurement ton equate to 40 cubic feet. [6] The ton is not an official unit of the International System of Units (SI), but the metric variant—known as the tonne and defined as exactly 1,000 kilogram s—is accepted for use alongside SI units due to its alignment with the kilogram and the SI prefix "kilo-". [7] This acceptance stems from the tonne 's adoption by the International Committee for Weights and Measures (CIPM) in 1879 , facilitating its integration in scientific and commercial contexts where SI compatibility is essential. [7] Non-metric tons, such as the short ton (2,000 pounds) common in the United States and the long ton (2,240 pounds) used in the United Kingdom , lack formal SI endorsement but remain prevalent in customary systems. [5] Symbols for the ton vary to distinguish variants: the general symbol is "t" for the tonne , while "tn" or "sh tn" may denote the short ton , and "lt" or "LT" the long ton . [8] In volume measurements, terms like "freight ton" or "measurement ton" emphasize the cubic capacity rather than weight, often applied to assess cargo space in shipping without direct mass correlation. [6] Scope and Variations The long ton predominates in the United Kingdom and other Commonwealth nations, where it serves as the standard unit for mass in various applications, while the short ton is the primary mass unit in the United States. In contrast, the metric tonne —defined as exactly 1,000 kilograms—has emerged as the global standard for mass measurements, influenced by the widespread adoption of the International System of Units (SI) in most countries outside the traditional imperial spheres. [9] Ton units encompass both mass-based and volume-based variants, with mass tons quantifying weight for commodities like cargo , and volume tons assessing capacity in contexts such as ship holds, where the two lack direct equivalence due to differing physical properties. For instance, the register ton, a volume measure, equates to 100 cubic feet of enclosed space , independent of the actual mass it might contain. Throughout the 20th century , international trade and scientific practices shifted toward the metric tonne as the preferred unit, aligning with broader metrication efforts to streamline global exchanges and precision in research . Imperial variants like the long and short tons persist in legacy sectors, including mining operations and maritime shipping, where historical conventions maintain compatibility with existing infrastructure. [10] The United Nations Economic Commission for Europe (UNECE) provides codes for units of measure used in international trade , incorporating standardized definitions for various tons to reduce discrepancies and support fair global transactions. [11] Etymology and History Etymology The term "ton" originates from the Old English word tunne , referring to a large cask or barrel used for storing wine, ale, or beer in Anglo-Saxon England , where it symbolized a standard unit of volume . [12] This usage traces back further to pre-12th-century influences, including Roman adoption of wooden barrel technology from the Gauls , whose Celtic term tondā —meaning "surface" or "skin"—evolved into the Latin tunna for a large container or tun. [13] North Sea Germanic languages, including those spoken by Viking traders, also contributed to the spread of similar barrel standards across Europe , reinforcing the term's association with large-scale liquid measures. [12] By the 12th century , Medieval Latin tunna had been integrated into English trade practices, where the barrel's contents began to denote a corresponding weight measure, marking the transition from volume to mass in commercial contexts. [14] The spelling shifted from "tun" to "ton" by the late 14th century, reflecting broader Middle English adaptations for a defined capacity in commodities like timber, stone, and iron. [15] In the 18th century , the French variant tonne —itself derived from the same Latin root—influenced the metric system's adoption of a standardized mass unit, distinguishing it from imperial forms. [16] Linguistic variations highlight the term's Indo-European roots tied to barrel measures: German employs Tonne for both volume and the metric ton, while Spanish uses tonelada , stemming directly from tonel (a large cask akin to the tun). [15] These cognates underscore a shared heritage in ancient container-based quantification across Romance and Germanic languages . [17] Historical Development The ton as a unit of mass originated in medieval England , where it was established in the 13th century primarily for the wool trade, England 's key export at the time. It was defined as 20 hundredweights, each consisting of 112 pounds, totaling 2,240 pounds, to standardize shipments of wool sacks that typically weighed around 364 pounds. This avoirdupois system emerged from earlier Roman and local measures but was formalized to facilitate commerce and taxation. These weights and measures aimed to reduce discrepancies in trade across regions and curb fraud in the wool market. [18] During the colonial period, the American colonies diverged from British standards by adopting the short ton of 2,000 pounds in the 18th century , simplifying calculations for local trades like coal and grain where a hundredweight of 100 pounds proved more practical than the imperial 112 pounds. This short ton persisted after independence, embedded in early U.S. commercial practices, while the long ton of 2,240 pounds remained standard in the British Empire for international shipping and bulk goods. The 19th century saw the rise of the metric tonne, defined during the French Revolution in 1795 as 1,000 kilograms—the mass of one cubic meter of water at 4°C—to create a decimal-based system independent of commodities. Although Britain permitted metric units in trade via the 1864 Weights and Measures Act following earlier discussions in the 1850s , imperial tons resisted widespread replacement due to entrenched industrial use. [18] [19] In the 20th century , legal shifts accelerated metrication in some regions while others clung to customary units. The UK's Weights and Measures Act 1985, implementing EU directives, retained definitions for both the long ton and the metric tonne but supported ongoing metrication efforts that limited non-metric units in trade, though supplementary imperial use lingered in legacy sectors. [20] In the United States, the short ton was retained through laws like the 1893 Mendenhall Order, which aligned yard and pound with metric prototypes but preserved customary units for domestic commerce , reinforced by ongoing federal standards. Entering the 21st century , EU mandates under Directive 80/181/EEC (amended in 2000) required primary use of SI units like the metric tonne for measurements in trade to ensure uniformity across borders. Meanwhile, imperial tons, particularly the short ton , persist in outdated U.S. aviation contexts for payload calculations, despite global shifts toward metric tonnes in international cargo operations. Units of Mass Long Ton and Short Ton The long ton , also known as the imperial ton or British ton, is a unit of mass equal to 2,240 avoirdupois pounds (1,016.0469 kilograms). It is defined as 20 hundredweight , with each hundredweight consisting of 112 pounds. This unit originated from the imperial system and remains recognized under UK regulations for supplementary indications alongside metric units. [21] [22] [23] The short ton , also called the US ton or net ton, is a unit of mass equal to 2,000 avoirdupois pounds (907.18474 kilograms). It comprises 20 hundredweight , each weighing 100 pounds, and forms part of the US customary system standa