# Units and Standards

## Unit Conversions Between Systems

For many years, an effort has been made to have the metric system, including SI units, adopted worldwide. As early as 1866, the United States Congress legalized the use of the metric system. More than a hundred years later, in 1976, the Congress adopted the Metric Conversion Act, declaring it the policy of the nation to increase the use of the metric system in the United States.

In fact, little progress has been made in that direction. Indeed, elements of the British system of measurement continue in use for specialized purposes throughout the world. All flight navigation, for example, is expressed in terms of feet, not meters. As a consequence, it is still necessary for an educated person to be able to convert from one system of measurement to the other.

In 1959, English-speaking countries around the world met to adopt standard conversion factors between British and metric systems. To convert from the pound to the kilogram, for example, it is necessary to multiply the given quantity (in pounds) by the factor 0.45359237. A conversion in the reverse direction, from kilograms to pounds, involves multiplying the given quantity (in kilograms) by the factor 2.2046226. Other relevant conversion factors are 1 inch = 2.54 centimeters and 1 yard = 0.9144 meter.

## Resources

### Books

Adams, Herbert F.R. *SI Metric Units: An Introduction.* Toronto: McGraw-Hill Ryerson, 1974.

Jerrard, H.G., and D.B. McNeil. *A Dictionary of Scientific* *Units: Including Dimensionless Numbers and Scales.* London: Chapman and Hall, 1980.

Nelson, Robert A. *SI: The International System of Units.* Stony Brook, NY: American Association of Physics Teachers, 1982.

David E. Newton

## Additional topics

Science EncyclopediaScience & Philosophy: *Two-envelope paradox* to *Venus*Units and Standards - History, The Metric System, Le Système International D'unités (the Si System), Derived Units