MeasurementMeasurement

Chapter 8Chapter 8

Why Measure?Why Measure? Measurement is the practice of Measurement is the practice of

comparing the qualities of an comparing the qualities of an object to a standard.object to a standard.

To describe objects using To describe objects using measurement, we have created measurement, we have created systems of standards of systems of standards of comparison.comparison.

Early MeasurementsEarly Measurements Early Egyptians, Romans, and Greeks Early Egyptians, Romans, and Greeks

used the human body to start an early used the human body to start an early system of measurement.system of measurement.

Foot – originally based on the size of a Foot – originally based on the size of a human foot.human foot.

Cubit – Length of an Arm from the elbow Cubit – Length of an Arm from the elbow to the tip of the middle finger (page to the tip of the middle finger (page 158).158).

Palm – Width of 4 FingersPalm – Width of 4 Fingers

Digit – Width of a Single Finger.Digit – Width of a Single Finger.

Today, each major physical quality is Today, each major physical quality is compared to a standard measurement that compared to a standard measurement that has been set by government standards.has been set by government standards.

The two measurement standards in use The two measurement standards in use in the world are:in the world are:

U.S. Customary or English (feet, U.S. Customary or English (feet, inches)inches)

International System of Units International System of Units (Metric)(Metric)

Current Measurement Current Measurement SystemsSystems

U.S. (English) System The U.S. customary system of measurement is The U.S. customary system of measurement is

based on the system that developed in England based on the system that developed in England from approximately the 1100s to the 1500s.from approximately the 1100s to the 1500s.

The system is confusing because of The system is confusing because of inconsistencies in computing fractions and inconsistencies in computing fractions and multiples of different base measurements.multiples of different base measurements.

For example, one inch is 1/12 of a foot, where as For example, one inch is 1/12 of a foot, where as one quart is ¼ of a gallon.one quart is ¼ of a gallon.

U.S. (English) U.S. (English) MeasurementMeasurementSome elements of ancient systems still Some elements of ancient systems still remain in the words we use.remain in the words we use.

Size:Size:Inch – means thumb in some languages.Inch – means thumb in some languages.There are 12 inches in a footThere are 12 inches in a footMile – 5,280 feet. Comes from the length of one Mile – 5,280 feet. Comes from the length of one thousand paces of a Roman legion.thousand paces of a Roman legion.

Volume:Volume:Quart – 4 quarts in a gallonQuart – 4 quarts in a gallonPint – 2 Pints in a quartPint – 2 Pints in a quart

The Metric SystemThe Metric System In the 1790s a group of French scientists In the 1790s a group of French scientists

assembled to create a measurement system assembled to create a measurement system that was more logical and exact.that was more logical and exact.

The metric system is also simpler because it The metric system is also simpler because it uses a prefix to show us how the base unit is uses a prefix to show us how the base unit is being changed. For example the unit for being changed. For example the unit for distance is the meter.distance is the meter.

The metric system uses the same prefixes for all The metric system uses the same prefixes for all base units.base units.

The metric system is considered to be a more The metric system is considered to be a more precise measurement system and is primarily precise measurement system and is primarily used in medicine and other industry where used in medicine and other industry where precise measurement is needed.precise measurement is needed.

Metric System Metric System MeasurementsMeasurements

Everything is based on 10.Everything is based on 10. Size:Size:

10 millimeters in a centimeter10 millimeters in a centimeter 10 centimeters in a decimeter10 centimeters in a decimeter 10 decimeters in a meter10 decimeters in a meter

Volume:Volume: 1,000 milliliters in a liter.1,000 milliliters in a liter.

Weight:Weight: 1,000 grams in a kilogram.1,000 grams in a kilogram.

U.S. Customary Metric

Inch Centimeter

Mile Kilometer

Degrees Fahrenheit

Degrees Celsius

Pound Kilogram

Gallon LiterThe second is the same for time measurement in both systems.

More About More About MeasurementMeasurement Several distance measurements may be used Several distance measurements may be used

when describing a part or product.when describing a part or product. The U.S. customary system The U.S. customary system ISIS NOTNOT built on the built on the

decimal system.decimal system. Precise measurements Precise measurements AREARE NOTNOT usually needed usually needed

when building a home.when building a home. Machinist’s rules are designed for finer Machinist’s rules are designed for finer

measurements than bench rules.measurements than bench rules. A sliding T-bevel A sliding T-bevel DOESDOES NOTNOT allow for a direct allow for a direct

reading when measuring an angle.reading when measuring an angle. The measurement tools an operator manipulates The measurement tools an operator manipulates

and reads and reads AREARE NOTNOT called indirect-reading called indirect-reading measurement tools.measurement tools.

MassMass is the amount of matter present in a is the amount of matter present in a material.material.

The gravitational pull exerted on an object is The gravitational pull exerted on an object is weightweight..

What can we What can we measure?measure? Size and SpaceSize and Space MassMass TemperatureTemperature TimeTime VolumeVolume SpeedSpeed DistanceDistance DimensionDimension

Size and SpaceSize and Space When we measure the size and When we measure the size and

shape of an object, we may shape of an object, we may encounter three different but related encounter three different but related measurements: length or distance, measurements: length or distance, area, and volume.area, and volume.

Measuring Length or Measuring Length or DistanceDistance

Length is the separation between two points.Length is the separation between two points.

Length: A & B

Thickness Width

Length and distance Length and distance are generally given are generally given in a single in a single measurement from measurement from Point A to Point B.Point A to Point B.

Many parts or Many parts or products are products are described as having described as having thickness, width, thickness, width, and heightand height

A

B

Measuring AreaMeasuring Area Determining the area of something Determining the area of something

involves measuring both length and involves measuring both length and width and then multiplying the two to width and then multiplying the two to determine how much surface the object determine how much surface the object covers.covers.

Length

Width

L x W = Area

Measuring VolumeMeasuring Volume The amount of space that an object The amount of space that an object

occupies or enclosesoccupies or encloses Volume is calculated by multiplying the Volume is calculated by multiplying the

length, width, and depth of an object. length, width, and depth of an object. L x W x D = Volume L x W x D = Volume

The measurement is expressed in cubic The measurement is expressed in cubic units.units.

Length

Width

Depth

Types of Types of MeasurementsMeasurements Standard Measurement:Standard Measurement: Measurement Measurement

that is close but not exact.that is close but not exact. Length of a piece of wood.Length of a piece of wood. Building a HouseBuilding a House Floor CoveringFloor Covering

Precision Measurement:Precision Measurement: Measurements Measurements accurate to 1/1,000th of an inch (and accurate to 1/1,000th of an inch (and smaller)smaller) Machine PartsMachine Parts Aircraft ComponentsAircraft Components

Measurement ToolsMeasurement Tools Ruler – most common measurement Ruler – most common measurement

tool – linear dimensions.tool – linear dimensions. Protractor – measures angles.Protractor – measures angles. Caliper – linear and diameterCaliper – linear and diameter Micrometer – used to measure linear Micrometer – used to measure linear

dimensions.dimensions. Sliding T-bevel Square – DOES NOT Sliding T-bevel Square – DOES NOT

allow for direct angle measurements.allow for direct angle measurements. Laser – indirect reading (processed by Laser – indirect reading (processed by

computer).computer). Optical Comparator - indirect reading Optical Comparator - indirect reading

(processed by computer).(processed by computer).

Why Measure?Why Measure? The foundation of a quality control The foundation of a quality control

system is measurement and analysis.system is measurement and analysis.

Measurement Measurement is not used to is not used to measure just measure just the output of the output of a technology a technology system, but all system, but all steps.steps.