LANGUAGE AND SYSTEMS OF MEASUREMENT

Accuracy can only be checked by comparison with:

• another technician or metrologist

• a trade group

• a higher standard

• your boss

Answer explanation

The precision of measurements often may be checked by repeatability. The accuracy can only be checked by comparison with a higher standard.

Measurement is most important to which one of the following applications?

• Mass production of automotive parts

• Mass production of aircraft parts

• One-of-a-kind handicrafts

• All manufacturing

• Manufacturing of parts from prepared plans

Answer explanation

Apart from the need for measurement in mass production, measurement is necessary whenever we make anything.

Measurement involves fundamental quantities. Select three base quantities from the following list:

• Roundness

• Mass

• Flatness

• Time

• Length

Answer explanation

Strictly speaking, metrology is the measurement of mass, length and time. From these primary quantities are derived all of the quantities involved in mechanics, electronics, hydraulics, ...

Which of the following best defines "dimensional metrology"?

• The measurements required to manufacture products

• Measurements found by the use of scales and other measuring instruments

• The measurement of lines, areas, volumes and angles

• The measurement of real things, whether they be steel, wood, plastic, or any other material

• The measurement of lines, circles and angles

Answer explanation

Mensuration or dimensional metrology is the branch of applied geometry that is concerned with finding the length of lines, areas of surfaces and volumes of solids from certain simple data pertaining to lines and angles.

For every act of dimensional metrology, one or more of the following variables may apply. Identify the single most important variable.

• Number of decimal places

• Metric or customary system

• Reliability

• Repeatability

• Sensitivity

Answer explanation

As an example, a skilled diemaker might use a micrometer to measure a given part to one-half thousandth of an inch. His experience and skill may enable him to do so with a high degree of reliability. If reliability is going to be the same, a much more sensitive instrument must be chosen.

Ambiguity is the enemy of dimensional metrology. Which of the following best describes a figure with four sides, each of which is 2.5 inches in length?

• Polyhedron

• Parallelepiped

• Square

• Parallelogram

Answer explanation

These four sides are equal, so, it must be a square

The principal dimensional measurement is length. Which of the following is the best definition of length?

• A dimension

• The shortest distance between two points

• The number of units of measurement that separates two points

• The opposite of width

Answer explanation

A linear measurement expresses the distance separating two points. Therefore, a measurement enables a distance to be reproduced.

Accuracy may be defined several ways. Which of the following is correct?

• Accuracy is the measure of precision

• Accuracy is the measure of conformity

• Accuracy is the measure of reliability

• Accuracy is the best synonym for precision

Answer explanation

Accuracy is also frequently called the "quality of conformity". Precision is called the "quality of refinement". And finally reliability shows the relationship between the predicted results and the actual ones.

How many .001 inches are there in one inch?

• 1

• 100

• 1,000

• 10,000

Answer explanation

Divide one inch by 0.001 inches, and you will get the result

Which of the following best explains the reasons for rounding off?

• Elimination of numbers over 5

• Averaging the computational error

• Elimination of meaningless digits

• Simplifying computations

Answer explanation

When we round off, we eliminate unnecessary figures in any computation.