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meas·ure·ment (mĕzhər-mənt)
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n.
1. The act of measuring or the process of being measured.
2. A system of measuring: measurement in miles.
3. The dimension, quantity, or capacity determined by measuring: the measurements of a room.

CONVERSION BETWEEN METRIC AND U.S. CUSTOMARY UNITS

FROM U.S. CUSTOMARY TO METRIC

When You KnowMultiply ByTo Find
inches25.4millimeters
 2.54centimeters
feet30.48centimeters
yards0.91meters
miles1.61kilometers
teaspoons4.93milliliters
tablespoons14.79milliliters
fluid ounces29.57milliliters
cups0.24liters
pints (liquid)0.47liters (liquid)
quarts (liquid)0.95liters (liquid)
gallons3.79liters
cubic feet0.028cubic meters
cubic yards0.76cubic meters
ounces28.35grams
pounds0.45kilograms
short tons (2,000 lbs)0.91metric tons
square inches6.45square centimeters
square feet0.09square meters
square yards0.84square meters
square miles2.59square kilometers
acres0.40hectares

FROM METRIC TO U.S. CUSTOMARY

When You KnowMultiply ByTo Find
millimeters0.04inches
centimeters0.39inches
meters3.28feet
 1.09yards
kilometers0.62miles
milliliters0.20teaspoons
 0.07tablespoons
 0.03fluid ounces
liters (liquid)1.06quarts (liquid)
 0.26gallons
 4.23cups
 2.12pints (liquid)
cubic meters35.31cubic feet
 1.35cubic yards
grams0.035ounces
kilograms2.20pounds
metric tons (1,000 kg)1.10short tons
square centimeters0.155square inches
square meters1.20square yards
square kilometers0.39square miles
hectares2.47acres

TEMPERATURE CONVERSION BETWEEN CELSIUS AND FAHRENHEIT

°C = (°F - 32) ÷ 1.8
°F = (°C × 1.8) + 32

UNITS OF THE INTERNATIONAL SYSTEM

The International System (abbreviated SI, for Système International, the French name for the system) was adopted in 1960 by the 11th General Conference on Weights and Measures. An expanded and modified version of the metric system, the International System addresses the needs of modern science for additional and more accurate units of measurement. The key features of the International System are decimalization, a system of prefixes, and a standard defined in terms of an invariable physical measure.

BASE UNITS

The International System has base units from which all others in the system are derived. The standards for the base units, except for the kilogram, are defined by unchanging and reproducible physical occurences. For example, the meter is defined as the distance traveled by light in a vacuum in 1/299,792,458 of a second. The standard for the kilogram is a platinum-iridium cylinder kept at the International Bureau of Weights and Standards in Sèvres, France.

UnitQuantity Symbol
meter length m
kilogram mass kg
second time s
ampere electric current A
kelvin temperature K
mole amount of matter mol
candela luminous intensity cd

PREFIXES

A multiple of a unit in the International System is formed by adding a prefix to the name of that unit. The prefixes change the magnitude of the unit by orders of ten from 1024 to 10-24.

PrefixSymbolMultiplying Factor
yotta- Y 1024 = 1,000,000,000,000,000,000,000,000
zetta- Z 1021 = 1,000,000,000,000,000,000,000
exa- E 1018 = 1,000,000,000,000,000,000
peta- P1015 = 1,000,000,000,000,000
tera- T 1012 = 1,000,000,000,000
giga- G 109 = 1,000,000,000
mega- M 106 = 1,000,000
kilo- k 103 = 1,000
hecto- h 102 = 100
deca- da 10 = 10
deci- d 10-1 = 0.1
centi- c 10-2 = 0.01
milli- m 10-3 = 0.001
micro- μ10-6 = 0.000,001
nano- n 10-9 = 0.000,000,001
pico- p 10-12 = 0.000,000,000,001
femto- f 10-15 = 0.000,000,000,000,001
atto- a 10-18 = 0.000,000,000,000,000,001
zepto- z 10-21 = 0.000,000,000,000,000,000,001
yocto- y 10-24 = 0.000,000,000,000,000,000,000,001

DERIVED UNITS

Most of the units in the International System are derived units, that is units defined in terms of base units and supplementary units. Derived units can be divided into two groupsthose that have a special name and symbol, and those that do not.

WITHOUT NAMES AND SYMBOLS
Measure ofDerivation
acceleration m/s2
angular acceleration rad/s2
angular velocity rad/s
density kg/m3
electric field strength V/m
luminance cd/m2
magnetic field strength A/m
velocity m/s

WITH NAMES AND SYMBOLS
UnitMeasure ofSymbolDerivation
coulomb electric charge C A·s
farad electric capacitance F A·s/V
henry inductance H V·s/A
hertz frequency Hz cycles/s
joule quantity of energy J N·m
lumen flux of light lm cd·sr
lux illumination lx lm/m2
newton force N kg·m/s2
ohm electric resistance ΩV/A
pascal pressure Pa N/m2
tesla magnetic flux density T Wb/m2
volt voltage V W/A
watt power W J/s
weber magnetic flux Wb V·s

Copyright © 2011 by Houghton Mifflin Harcourt Publishing Company


The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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