A cylinder that weighs exactly 1 kilogram is
kept by the International Bureau of Weights
and Measures in Paris, France. The kilogram
is a unit of weight in the metric system
of measurement.
88 Measurement BRITANNICA STUDENT ENCYCLOPEDIA
unit of weight. Units may also be
divided into smaller units. For example,
a foot is a unit of length that may be
divided into 12 smaller units, called
inches. Measuring instruments, such as
scales and rulers, are marked with these
units.
All standards belong to a particular system
of measurement. Throughout history,
people have come up with many
systems of measurement. Each system
has its own set of standards. That is,
each has a different way of measuring.
Pounds and kilograms are both units of
weight, but each belongs to a different
system. Therefore a box that weighs 2.2
pounds in one system weighs 1 kilogram
in another. The two most widely used
systems are the English system and the
metric system.
English System
The system of measurement most
commonly used in the United States is
based on the English system. This
system developed in England, and
English settlers brought it to the
American colonies.
In this system the inch is a unit of
length. There are 12 inches in 1 foot and
5,280 feet in 1 mile. The cup is a unit of
volume (used to measure liquids). There
Some Metric Prefixes
Prefix Name Equal to Examples
mega million 1,000,000 One megabyte equals one million bytes. (A byte is a
unit of measurement for computer storage space.)
kilo thousand 1,000 One kiloliter is equal to one thousand liters.
hecto hundred 100 One hectogram is equal to one hundred grams.
deka (also ten 10 One decameter is equal to ten meters.
spelled deca)
deci tenth 0.1 One deciliter is equal to one tenth of a liter.
centi hundredth 0.01 One centimeter is equal to one hundredth of a meter.
milli thousandth 0.001 One millisecond is equal to one thousandth of a second.
micro millionth 0.000001 One microgram is equal to one millionth of a gram.
Note: To convert from one metric measurement to another, simply move the decimal point in the measurement
being converted. For example, to convert millimeters to centimeters, move the decimal point over one place to
the left. 27 millimeters is equal to 2.7 centimeters. To convert kilograms to decigrams, move the decimal point
four places to the right. 3.3 kilograms is equal to 33,000 decigrams.
Some Basic Measures in the
U.S. Measurement System
Length
12 inches = 1 foot
3 feet = 1 yard
5,280 feet = 1 mile
Weight
16 ounces = 1 pound
2,000 pounds = 1 ton
Liquid Volume
16 fluid ounces = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon
Area
640 acres = 1 square mile
Cooking
3 teaspoons = 1 tablespoon
2 tablespoons = 1 fluid ounce
8 fluid ounces = 1 cup
BRITANNICA STUDENT ENCYCLOPEDIA Measurement 89
are 2 cups in 1 pint, 2 pints in 1 quart,
and 4 quarts in 1 gallon. The ounce is a
unit of weight. There are 16 ounces in 1
pound and 2,000 pounds in 1 ton.
Many of the names for these units come
from the fact that, at first, people used
everyday objects to measure things. The
length of a person’s foot was used to
measure short distances. A household
cup might be used to measure liquids.
But without standards, these measurements
were not the same for everyone.
Eventually people set standards, and the
English system became the first worldwide
system of measurement.
Metric System
In the 1790s France developed the metric
system of measurement. By the
middle of the 1900s most countries had
adopted this system. In the metric system,
each kind of measurement has one
basic unit. The meter is the basic unit of
length, the gram is the unit of weight,
and the liter is the unit of volume. Each
unit is divided into smaller units or
combined into larger units by multiples
of 10.
Standard prefixes, or parts of words, are
added to the beginning of the basic unit
to tell how many multiples of 10 are in a
unit. For example, “kilo-” means “thousand”
so there are 1,000 meters in 1
kilometer. And “centi-” means “1/100” so
1 meter is equal to 100 centimeters.
Mecca
Population
(2007
estimate), urban
area,
1,385,000
Mecca is a city in Saudi Arabia, a country
in the Middle East. The city was the
birthplace of Muhammad, the founder
of Islam. Muslims all over the world
turn toward Mecca to pray five times
each day. It is the world’s holiest city to
Muslims. Because of that, only Muslims
are allowed to enter Mecca.
Every Muslim who is able to must make
a religious journey, or pilgrimage, to
Mecca at least once. The pilgrims visit
the Great Mosque. In the mosque’s
courtyard is the holy Ka!bah, a small
Some Conversions Between U.S.
and Metric Measurements
Length
1 inch = 2.54 centimeters
1 foot = 0.3048 meter
1 mile = 1.6093 kilometers
1 centimeter = 0.3937 inch
1 meter = 3.2808 feet
1 kilometer = 0.62137 mile
Liquid Volume
1 quart = 0.9463 liter
1 gallon = 3.785 liters
1 liter = 1.0567 quarts
1 liter = 0.2642 gallon
Weight
1 pound = 0.45359 kilogram
1 kilogram = 2.2046 pounds
90 Mecca BRITANNICA STUDENT ENCYCLOPEDIA
building that contains the Black Stone
of Mecca. Legend says that the stone was
given to Adam, the first man, when he
