Units of Measurement 112

2D

two-dimensional. Having length and width, but not depth. 2D shapes are flat.

3D

Three-dimensional. Having length, width, and height. 3D objects occur within three planes of space.

area

A measurement of the amount of space contained within a flat, enclosed shape. Area is determined by multiplying the length and width of the shape.

axis

An imaginary straight line that passes through the center of an object. A cylindrical component typically rotates around its axis.

balance scale

A scale that uses two platforms on either side of a fulcrum to compare the weights of objects. Balance scales are also known as balances, beam balances, or laboratory balances.

base units

A unit of measurement used for measurements that can be determined by taking one single measurement. Base units measurements include distance, mass, time, and temperature.

caliper

A measuring instrument that includes one or more sets of jaws and a scale marked with unit divisions. Calipers often include one set of jaws to measure outer diameters and another set of jaws to measure internal diameters.

capacity

A metric hat indicates the amount of liquid a component can contain. Capacity may be referred to as volume.

Celsius scale

A temperature measurement scale used in the metric system that is divided into degrees Celsius. On the Celsius scale, the freezing point of water is 0 degrees and the boiling point is 100 degrees.

centimeter

cm. A unit of linear measurement in the metric system that is equal to 0.01 meters. One centimeter equals 0.394 inches in the English system.

centimeters per minute

cpm. A unit of linear speed measurement in the metric system that is used for objects that travel shorter distances. Centimeters per minute is typically used to measure machine tool speed.

coordinate measuring machines

CMM. A sophisticated measuring instrument with a flat polished table and a suspended probe that measures parts in three-dimensional space. Coordinate measuring machines can measure using either contact or noncontact methods.

cubed

Multiplied by itself two times. Cubed values have an exponent of three.

cubic centimeter

cm³. A unit of volume measurement in the metric system equal to 1 milliliter. Once cubic centimeter is equal to 0.0610237 cubic inch in the English system.

cubic foot

ft.³. A unit of volume measurement in the English system equal to 1728 cubic inches. Once cubic foot is equal to 0.028 cubic meters.

cubic inch

in.³. A unit of volume measurement in the English system that is equal to 0.000578 cubic feet. One cubic inch equals 16.387 milliliters in the metric system. One cubic inch equals 16.387 milliliters in the metric system.

cubic meter

m³. A unit of volume measurement in the metric system that is equal to 1,000,000 cubic centimer. One cubic meter, or one kiloliter, is equal to 35.315 cubic feet in the English system.

cubic yard

yd.³. A unit of volume measurement in the English system that is equal to 27 cubic feet. One cubic yard equals 0.765 cubic meters in the metric system.

cutting tool

A device made of hard, tough material that is used to remove metal by creating chips. Cutting tools are either single or multi-point tools.

degrees

A unit used to indicate a specific amount of change on a scale. Degrees are used to measure temperature.

degrees Celsius

°C. A unit of temperature measurement used in the metric system. One degree Celsius is equal to 33.8° Fahrenheit and 274.16 kelvins.

degrees Fahrenheit

°F. A unit of temperature measurement used in the English system. One degree Fahrenheit is equal to -17.2° Celsius and 255.928 kelvins.

density

The amount of mass within a specific volume of a substance. Objects with greater density have increased mass and weight.

derived units

A unit of measurement that results from combining two or more base units. Derived unit measurements include area, volume, and speed.

diameter

The distance from one edge of a circle to the opposite edge as measured through the center. The radius of a circle is half the diameter.

distance

The amount of linear space between two points or objects. Distance can measure the amount of space between objects or the dimensions of an object, such as length and width.

English system

A standard system of measurement based on the inch, pound, and gallon. The English system is primarily used in the United States and England.

exponents

A mathematical operation indicating how many times a number is multiplied by itself. Exponents of ten are also known as powers.

Fahrenheit scale

The temperature measurement scale used in the English system that is divided into degrees Fahrenheit. On the Fahrenheit scale, the freezing point of water is 32 degrees and the boiling point is 212 degrees.

foot

ft. A unit of linear measurement in the English system that equals 12 inches. One foot equals 30.48 centimeters or 0.30 meters in the metric system

foot

ft. A unit of linear measurement in the English system that is equal to 12 inches. One foot equals 30.48 centimeters in the metric system.

gallon

gal. A unit of volume measurement in the English system equal to 16 cups One gallon equals 3.785 liters in the metric system.

gram

g. A unit of mass measurement in the metric system that is equal to 0.001 kilograms. One gram equals 0.035 ounces in the English system.

gravity

The force exerted by the Earth on other objects at or near its surface. Gravity pulls on the entire mass of an object.

gravity

The force of attraction between masses. Gravity is the force that makes objects fall to the ground.

height

a perpendicular line drawn from the highest point in the triangle to the base on the opposite side. Height and base are always perpendicular.

Imperial system

A recognized system of measurement adopted by the United Kingdom, Canada, and other affiliated countries in 1824. The imperial system is still in use for some measurements such as speed, distance, and volume but has largely been replaced with metric system since 1965.

inch

in. A unit of linear measurement in the English system that is equal to 0.083 feet. One inch equals 2.54 centimeters in the metric system.

inches per minute

ipm. A unit of linear speed measurement in the English system that is used for objects that travel shorter distances. Inches per minute is typically used to measure machine tool speed.

International System of Units

SI. An internationally recognized standard system of measurement based on the gram, liter, and meter. The International System of Units is also known as the metric system.

Kelvin scale

A scientific temperature measurement scale used in the metric system that is divided into kelvins (K). On the Kelvin scale, the freezing point of water is 273.15 K and the boiling point is 373.15 K.

Kelvins

K. • kelvins: K. A unit of temperature measurement used in the metric system for scientific measurements. One kelvin is equal to -457.87° Fahrenheit and -272.15° Celsius.

kilogram

kg. A unit of mass measurement in the metric system that is equal to 1000 grams. One kilogram is equal to 2.205 pounds in the English system.

kiloliter

kL. A unit of volume measurement in the metric system that is equal to 1,000,000 milliliter. One kiloliter, or one cubic meter is equal to 35.315 cubic feet in the English system.

kilometer

km. A unit of linear measurement in the metric system that is equal to 1,000 meters. One kilometer equals 0.621 miles in the English system.

kilometers per hour

kph. A unit of linear speed measurement in the metric system that is used for objects that travel long distances quickly. Kilometers per hour is typically used to measure vehicle speed.

length

An object's measurement from end to end, rather than from side to side. Length is one of three key dimensions, along with width and height.

linear speed

The rate at which an object travels along a straight path. Linear speed is often expressed as inches per minute or centimeters per minute.

liter

L or l. A unit of volume measurement in the metric system that is equal to 1,000 milliliters. One liter equals 4.227 cups in the English system.

mass

The amount of matter contained within an object. Mass gives an object weight and is measured with metric units.

matter

A substance that has mass and exists as a solid, liquid, or gas. Matter can change states based on temperature and pressure.

measurement

The act or process of determining the distance, mass, weight, time, temperature or other physical aspect of an object, event, or phenomenon. Measurement results can be expressed in English system or metric system units.

meter

m. A base unit of linear measurement in the metric system. One meter equals 3.28 feet in the English system.

meter

m. A unit of length measurement in the metric system. One meter is equal to 100 centimeters metric and 3.281 feet.

metric system

An internationally recognized standard system of measurement based on the gram, liter, and meter. The metric system is also known as the International System of Units (SI).

metric ton

mt. unit of weight in the metric system. One metric ton is equal to 1000 kilograms and 1.10231 tons in the English system.

micrometer

A U-shaped measuring instrument with a threaded spindle that slowly advances toward a small anvil. Micrometers are available in numerous types for measuring assorted dimensions and features.

mile

mi. A unit of linear measurement in the English system that equals 5,280 feet. One mile equals 1,609.34 meters or 1.61 kilometers in the metric system.

miles per hour

mph. A unit of linear speed measurement in the English system that is used for objects that travel long distances quickly. Miles per hour is typically used to measure vehicle speed.

milligram

mg. A unit of mass measurement in the metric system that is equal to 0.001 grams. One milligram is equal to 0.0000353 ounces in the English system.

milliliter

mL. A unit of volume measurement in the metric system that is equal to 0.001 liters. One milliliter, or one cubic centimeter, equals 0.0610 cubic inches in the English system.

millimeter

mm. A unit of linear measurement in the metric system that is equal to 0.1 centimeters. One millimeter equals 0.039 inches in the English system.

ounce

oz. A unit of weight measurement in the English system that is equal to 0.063 pounds. One ounce equals 28.35 grams in the metric system.

pound

lb. A unit of weight measurement in the English system that is equal to 16 ounces. One pound equals 0.454 kilograms in the metric system.

powers

A mathematical operation indicating how many times a number is multiplied by itself. Powers of ten are also known as exponents.

prefix

A word or combination of letters added to the beginning of a word to modify its meaning. Prefixes are added to metric units of measurement to indicate powers of ten.

revolutions per minute

rpm. A unit of rotary speed measurement that indicates how many complete rotations an object makes in one minute. Revolutions per minute is used in both the English and metric systems.

rotary speed

The rate at which an object rotates around its axis. Rotary speed is measured by counting the number of revolutions that occur in a specific amount of time.

speed

The amount an object travels in a given period of time. Speed can describe linear or rotational motion.

spindle

A component of a machine tool that rotates the workpiece or cutting tool. Spindle speed is measured in revolutions per minute.

square centimeter

cm². A unit of area measurement in the metric system that is equal to 100 square millimeters. One square centimeter equals 0.155 square inches in the English system.

square foot

ft². A unit of area measurement in the English system that is equal to 144 square inches. One square foot equals 0.093 square meters in the metric system.

square inch

in². A unit of area measurement in the English system that is equal to 0.007 square feet. One square inch equals 6.452 square centimeters in the metric system.

square kilometer

km².A unit of area measurement in the metric system that is equal to 1,000,000 square yards. One kilometer equals square miles in the English system.

square meter

m².A unit of area measurement in the metric system that is equal to 10,000 square centimeters. One square meter equals 10.764 square feet in the English system.

square mile

mi².A unit of area measurement in the English system that is equal to 3097600 square yards. One square mile equals 2.58999 square kilometers in the metric system.

square mile

mi.². A unit of area measurement in the English system that is equal to 3097600 square yards. One square mile equals 2.58999 square kilometers in the metric system.

square millimeter

mm². A unit of area measurement in the metric system that is equal to 0.01 square centimeters. One square millimeter equals 0.002 square inches in the English system.

square yard

yd². A unit of area measurement in the English system that is equal to 9 square feet. One square yard equals 0.836 square meters in the metric system.

squared

Multiplied by itself. Squared values have an exponent of two.

temperature

A measurement of the amount of thermal energy in a substance. Temperature is measured in degrees.

thermal energy

Power created by or in the form of heat. Thermal energy can be retained in machine parts and cause burns.

thermodynamics

The branch of physics that studies energy in transitional states. Any process involving energy, heat, and work can be explained through the first two laws of thermodynamics.

thermometers

A thermal device that measures temperature. Thermometers are typically calibrated to either the Celsius or Fahrenheit temperature scale.

three-dimensional

3D. Having length, width, and height. Three-dimensional objects occur within three planes of space.

time

A measurement of how long an event takes to occur from start to finish. Time is measured in seconds, minutes, and hours.

tolerance

An acceptable deviation from a desired dimension that still meets part specifications. Tolerances indicate the allowable difference between a physical feature and its intended design.

ton

T. A unit of weight measurement in the English System that is equal to 2,000 pounds. One ton equals 907.185 kilograms in the metric system.

two-dimensional

2D. Having length and height, but not depth. Two-dimensional shapes are flat.

U.S. customary system

A standard system of measurement used in the United States that is based on the inch, pound, and gallon. The U.S. customary system is the formal name for the English system of measurement used in the United States and varies slightly from the Imperial system used in England.

units

• units: A pre-determined quantity used as a measurement standard. Units are used in measuring systems to indicate distance, temperature, speed, weight, mass, time, and more.

volume

A measurement of the amount of space contained within a three dimensional object.  The volume of a cube is equal to its height multiplied by its width and length.

volume

A measurement of the amount of space contained within a three-dimensional space. Volume is determined by multiplying the length, width, and height of the shape.

weight

A measurement of the gravitational pull on an object on the earth's surface. Weight is expressed in the English system using the pound or the ounce and in the metric system using milligrams, grams, and kilograms.

weight

A measurement of the gravitational pull on an object on the surface of the earth. Weight is determined by object mass and is measured with English units.

width

An object’s measurement from side to side, rather than from end to end. Width is a key dimension, along with length and diameter.

yard

yd. A unit of linear measurement in the English system that is equal to 3 feet. One yard equals 0.914 meters in the metric system.