Unit conversions are one of the worst nightmares experienced by hapless elementary school students. How many inches are there in a foot? Twelve. How many feet are there in a yard? Three. How many yards are there in a mile? One thousand, seven hundred and sixty.
Despite being different physical quantities, mass and weight share a similar pattern of conversions. There are 16 ounces in a pound, 14 pounds in a stone, 2000 pounds in a short (U.S.) ton and 2240 pounds in a long (British) ton.
The good news is that unit conversions for volume are straightforward. A gill is four fluid ounces; a cup is two gills; a pint is two cups; a quart is two pints; and a gallon is four quarts.
Yet, to complicate matters further, there exist area and volume analogs of inches, feet and miles. A square foot has 144 square inches, nine square feet in a square yard, 4840 square yards in an acre and 640 acres in a square mile.
Volume analogs follow a similar trend, and at first glance, they seem different from the cups and gallons mentioned previously. Thanks to some dimensional analysis, one gallon is equal to 231 cubic inches.
These unit conversions are so easy to remember that it’s no surprise they are widespread throughout the United States. In fact, they are given their own special name: U.S. customary units, which are similar to the outdated imperial system apart from subtle differences in terminology.
With the exception of the United States, Liberia and Myanmar, all countries have officially adopted the metric system. We find ourselves in a unique predicament, which can possibly be attributed to American exceptionalism. Alternatively, the rest of the world is doing something right, and we are simply resistant to change.
Photo Courtesy Canuckguy/Wikipedia
The countries shaded in green are those that have adopted the metric system.
Why is the metric system so popular? The obvious reason is that the metric system is easy to learn, since the units are scaled by multiples of 10. Decimals simplify unit conversions and standardize the metric system.
Under the U.S. customary system, one gallon is equal to 231 cubic inches. Fortunately, the metric system simply defines one liter to be equivalent to a cubic decimeter, or 1000 cubic centimeters. A liter is a little more than a quart, so volume is readily metricated. In addition, the metric system avoids unit duplications. As mentioned previously, mass and weight are different physical quantities, but share the same unit of pound. Under a strict classification of base and derived units, the metric system is unambiguous, whereby weight is expressed in newtons, while mass is expressed in kilograms.
The metric system is also consistent and versatile. The U.S. customary system has limited scope, since it is only applicable to convenient measures, such as length and mass. Yet, this system doesn’t provide alternatives to the electrical units of volts and amperes, or the chemical units of moles and katals.
When we drive, we are aware that distance is measured in miles, and speed is measured in miles per hour. How is acceleration measured? Miles per hour per second and miles per hour per hour are possible alternatives, but they are too convoluted to have any meaningful value.
The metric system solves the problem by expressing acceleration in terms of meters per second squared. Speed can be expressed in kilometers per hour. Dividing by 3.6 gives an equivalent result depicted in meters per second, from which acceleration can be easily found.
Metrication also has significant economic benefits. Since the rest of the world employs the metric system, metrication in the United States will strengthen and expedite trade with other nations. Standard rules used under the metric system will improve efficiency and foster technological progress.
However, criticizing the United States for failing to metricate is demeaning and inaccurate. For instance, Fahrenheit scale and calories are useful in meteorology and chemistry respectively. Moreover, metric prefixes like kilo- and mega- are used in finance, computer science and even in ordinary conversations.
Currently, both the U.S. customary system and the metric system are used. Yet, the continued use of the U.S. customary system remains a problem due to its numerous drawbacks. Metrication opponents are simply too resistant to adapt, and they justify their stance with incorrect scientific claims.
From a historical perspective, metrication opponents are traditionalists. The U.S. customary system is derived from the outdated imperial system used by the British Empire, which in turn originated from an arbitrary medieval system of weights and measures.
During the French Revolution, a group of French scientists led by Antoine Lavoisier and Pierre-Simon Laplace developed the metric system based on principles that relate length, volume and mass. This metric system is called the International System of Units.
From Article I, Section 8 of the Constitution, Congress has the power to fix the standard of weights and measures. Yet, when the first Congress convened in 1789, the metric system was only at its infancy.
Instead, Thomas Jefferson proposed a decimal system that was surprisingly similar to the metric system. Sadly, he didn’t use prefixes, so his system contained a long list of names. Lacking sufficient scientific support, Congress took no action, so Americans were stuck with the confusing imperial system.
Tragically, relations between France and the United States deteriorated, especially after the ratification of Jay’s Treaty in 1795 that improved American commerce with Britain. Additional problems from the XYZ Affair and Quasi-War led France to snub American delegates who were interested in learning about the metric system.
Consequently, Americans kept the imperial system, so that they could focus on pressing issues and controversies. After the American Civil War, most of Europe had metricated. As such, Congress passed the Metric Act of 1866, which authorized the use of the metric system.
The metric system was favored by scientists and business leaders for a single obvious reason: efficiency. In 1875, the United States signed the Treaty of the Meter, which established the International Bureau of Weights and Measures.
In 1893, Thomas Corwin Mendenhall, who served as the superintendent of Weights and Measures in the Treasury Department, declared that the metric standards should be used to define all customary units of American measurement. Legally, a foot is exactly equal to 0.3048 meters, while a pound is exactly equal to 453.59237 grams.
Scientists, engineers, business leaders and the government all supported the metric system, so Congress passed the Metric Conversion Act of 1975 to accelerate metrication. The United States would finally join the rest of the world by adopting the metric system.
Shockingly, metrication efforts were halted by a steadfast group: the American public. Curiously, the American public was also responsible for resisting the Metric Act of 1866 and stalling the Mendenhall Order.
Popular opposition is mainly due to a matter of convenience, and American consumers confidently believed that metrication would obscure weather reports and distance measurements. This is ironic since U.S. customary units have complex conversions, while “convenient” measures are easily metricated.
Clearly, consumer stubbornness to stick with the U.S. customary units would hurt trade. As a result, Congress passed the Omnibus Foreign Trade and Competitiveness Act of 1988, which made the metric system as the preferred system used for trade and commerce.
My message to the American public: Support the metric system. The U.S. customary system is irregular, redundant and confusing, which not only complicates math education for children, but also hinders economic growth.
Short-term costs are inevitable, but they can be minimized through a gradual and complete transition. Let’s expedite the metrication process to bolster international commerce and avoid preventable economic difficulties in the long term.
Badri Karthikeyan is a senior biology major at Drexel University. He can be contacted at op-ed@thetriangle.org.
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