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There are two major systems of measurement in use today. They are the United States system and the metric system . Before we describe these systems, let's gain a clear understanding of the concept of measurement.
Over the years, standards have changed. Quite some time in the past, the standard unit of measure was determined by a king. For example,
1 inch was the distance between the tip of the thumb and the knuckle of the king.
1 inch was also the length of 16 barley grains placed end to end.
Today, standard units of measure rarely change. Standard units of measure are the responsibility of the Bureau of Standards in Washington D.C.
Some desirable properties of a standard are the following:
Some of the common units (along with their abbreviations) for the United States system of measurement are listed in the following table.
Unit Conversion Table | |
Length | 1 foot (ft) = 12 inches (in.)
1 yard (yd) = 3 feet (ft) 1 mile (mi) = 5,280 feet |
Weight | 1 pound (lb) =16 ounces (oz)
1 ton (T) = 2,000 pounds |
Liquid Volume | 1 tablespoon (tbsp) = 3 teaspoons (tsp)
1 fluid ounce (fl oz) = 2 tablespoons 1 cup (c) = 8 fluid ounces 1 pint (pt) = 2 cups 1 quart (qt) = 2 pints 1 gallon (gal) = 4 quarts |
Time | 1 minute (min) = 60 seconds (sec)
1 hour ( hr) = 60 minutes 1 day (da) = 24 hours 1 week (wk) = 7 days |
It is often convenient or necessary to convert from one unit of measure to another. For example, it may be convenient to convert a measurement of length that is given in feet to one that is given in inches. Such conversions can be made using unit fractions .
Unit fractions are formed by using two equal measurements. One measurement is placed in the numerator of the fraction, and the other in the denominator. Placement depends on the desired conversion .
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