1.2-3 Accuracy of Measurements-Measurement of Distances

Question 1

process of determining the extent, size or dimensions of a particular quantity in comparison to a given standard.

Answer 1

measurement

Question 2

2 types of measurements

Answer 2

direct measurements
indirect measurements

Question 3

a comparison of the measured quantity with a standard measuring unit or units employed for measuring a quantity of that kind.

Answer 3

Direct Measurements

Question 4

applying a wire or tape to a line is an example of what type of measurement

Answer 4

Direct Measurements

Question 5

determining a horizontal or vertical angle with a transit is an example of what type of measurement

Answer 5

Direct Measurements

Question 6

fitting a protractor between two intersecting lines to
determine the intersection angle is an example of what type of measurement

Answer 6

Direct Measurements

Question 7

When it is not possible to apply a measuring instrument directly to a quantity to be measured

Answer 7

Indirect Measurements

Question 8

In this type of measurement, the observed value is
determined by its relationship to some other known
values.

Answer 8

Indirect Measurements

Question 9

the difference between the true value and the measured value of a quantity

Answer 9

Errors

Question 10

inherent in all measurements and results from sources which cannot be avoided.

Answer 10

Errors

Question 11

inaccuracies in measurements which occurred because some aspect of a surveying operation is performed by the surveyor with: carelessness, poor judgment, inattention, and improper execution

Answer 11

Mistakes

Question 12

are also caused by: misunderstanding the problem, inexperience, and indifference of the surveyor

Answer 12

Mistakes

Question 13

reading the wrong graduation of the tape is an example of

Answer 13

Mistakes

Question 14

transposition of figures is an example of

Answer 14

Mistakes

Question 15

reading a scale backward is an example of

Answer 15

Mistakes

Question 16

misplacing a decimal point is an example of

Answer 16

Mistakes

Question 17

incorrect reading of field notes is an example of

Answer 17

Mistakes

Question 18

2 types of errors

Answer 18

Systematic and Accidental

Question 19

type of error that will always have the same sign and
magnitude as long as field conditions remain constant and
unchanged.

Answer 19

Systematic Errors

Question 20

how to eliminate systematic errors (3)

Answer 20

(1) applying corrections
(2) employing proper techniques in the use of instruments
(3) adopting a field procedure which automatically eliminates the error

Question 21

purely accidental in character caused by factors beyond the control of the surveyor and are present in all surveying measurement

Answer 21

Accidental Errors

Question 22

The occurrence of such errors are matters of chance as they
are likely to be positive or negative, and may tend in part to
compensate or average out according to ___

Answer 22

laws of probability

Question 23

due to imperfections in the instruments used, either from faults in their construction or improper adjustments between the different parts prior to their use.

Answer 23

Instrumental Errors

Question 24

caused by variations in the phenomena of nature such as: temperature, gravity, wind, humidity, curvature of the earth, and refraction changes in magnetic declination

Answer 24

Natural Errors

Question 25

Sources of errors (3)

Answer 25

Instrumental Errors Natural Errors Personal Errors

Question 26

arise from limitations of the human observer's senses of sight, touch, and hearing, which are likely erroneous or inaccurate.

Answer 26

Personal Errors

Question 27

indicates how close a given measurement is to the absolute or true value of the quantity measured.

Answer 27

Accuracy

Question 28

refers to the degree of refinement and consistency with which any physical measurement is made.

Answer 28

Precision

Question 29

portrayed by the closeness to one another of a set of repeated measurements of a quantity.

Answer 29

Precision

Question 30

number of times something will probably occur over the range of possible occurrences.

Answer 30

Probability

Question 31

the quantity which, based on available data, has more chances of being correct than any other.

Answer 31

MOST PROBABLE VALUE (MPV)

Question 32

total amount of error in a given measurement should relate to the magnitude of the measured quantity in order to indicate the accuracy of a measurement.

Answer 32

RELATIVE (ERROR) PRECISION

Question 33

expressed by a fraction having the magnitude of the error in the numerator and the magnitude of a measured quantity in the denominator.

Answer 33

RELATIVE (ERROR) PRECISION

Question 34

quantity which, when added to and subtracted from the most probable value, defines a range within which there is a 50 percent chance that the true value of the measured quantity lies inside (or outside) the limits thus set.

Answer 34

PROBABLE ERROR

Question 35

The estimated degree of reliability (or weight) for each of the measurements before they are combined and the most probable values are determined.

Answer 35

WEIGHTED OBSERVATIONS

Question 36

Methods of Distance Measurement (8)

Answer 36

1. Pacing 5. Mathematical 2. Taping 6. Mechanical 3.Tachymetric 7. Photogrammetric 4. Graphical 8. Electronic Distance Measurement

Question 37

consists of counting the number of steps or paces in a required distance.

Answer 37

Pacing

Question 38

A ___ is defined as the length of step in walking.

Answer 38

pace

Question 39

To pace a distance, one must first determine the length of one's pace. This is referred to as the___.

Answer 39

pace factor

Question 40

___ is another procedure of obtaining horizontal distances. It is based on the optical geometry of the instruments employed and is an indirect method of measurement.

Answer 40

Tachymetry

Question 41

A rapid means of determining horizontal distances.

Answer 41

Stadia Method

Question 42

is a convenient and practical device used for quick and accurate measurement of horizontal distances.

Answer 42

The subtense bar

Question 43

These methods are widely employed in plane table surveys, and in triangulation works. In inaccessible terrain, this method becomes quite practical to employ.

Answer 43

Distance by Graphical and Mathematical Methods

Question 44

These devices are only applicable for low-precision surveys or where quick measurements are desired. The more commonly used among these devices include the odometer, measuring wheel, and optical range finder.

Answer 44

Distance by Mechanical Devices

Question 45

a simple device that can be attached to a wheel for purposes of roughly measuring surface distances.

Answer 45

Odometer

Question 46

This device can be used to determine distances approximately simply by focusing.

Answer 46

Optical Rangefinder

Question 47

refers to the measurement of images on a photograph.

Answer 47

Photogrammetry

Question 48

The tape ___ as the temperature rises and ___ as the temperature falls.

Answer 48

lengthens; shortens