This document provides an introduction to work study, which is a systematic approach to analyzing work processes with the goal of improving productivity and worker safety. It defines work study as examining work activities to effectively use resources and set performance standards. The key techniques of work study are mentioned as method study to analyze and improve work methods, and time study to establish standard times for tasks. The document outlines the basic procedure of work study and discusses how it can enhance productivity by simplifying work and reducing waste.

1. Unit- II
WORK STUDY
1

2. INTRODUCTION
• With increasing complexities of the
technological world, need to simplify the work
system has been increasing day by day.
• Work study is an area of knowledge that
addresses the problem of work simplification
with the basic objectives of
1. PRODUCTIVITY ENHANCEMENT, and
2. HUMAN COMFORT & SAFETY
2

3. “WORK STUDY” HAS MANY OTHER NAMES
FOR EXAMPLE
• METHODS ENGINEERING,
• WORK SCIENCE,
• WORK DESIGN,
• JOB ESIGN
• WORK METHODS DESIGN &WORK
MEASUREMENT
• MOTION &TIME STUDY
Original names were:
Motion study, Time Study
& then, Motion & Time Study
3

4. DEFINITION
It is the systematic study of work systems with
the purposes of
1. Developing the preferred system and Method
( with lowest cost)
2. Standardizing this system and method
3. Determining standard time for the task
4. Assisting in training the worker in the
preferred Method
4

5. EXPLANATION
Above stated definition has FOUR parts.
However, the TWO most important for WORK
STUDY are:
1.MOTION STUDY
(or Work Methods Design) &
2. TIME STUDY
(or Work Measurement)
5

6. ILO DEFINITION
“It is the systematic examination of
carrying on activities so as to
improve the effective use of
resources and to set standards of
performance for the activities being
carried out”.
6

7. WORK STUDY & PRODUCTIVITY
7

8. HUMAN’S BASIC NEEDS & PRODUCTIVITY
In 1950: world population was 2.5 b
Now : it is of the order of 7 b
90% increase has occurred in developing
nations.
8

9. Out of these people, more than
1 b are below poverty line, struggling
for the
BASIC NEEDS which are :
• food,
• clothing,
• shelter,
• security,
• health and
• essentials like water, sanitation etc.
9

10. For Improving the STANDARD OF LIVING, of
its citizens, the concerned nation must raise its
PRODUCTIVITY for economic growth. For any
organization, its input-output system can be
represented as follows:
PROCESS
INPUT OUTPUT
10

11. INPUTS may be in the form of different M’s:
man, material, machine,
method, management, market, message
( i.e. information), moment (i.e. time )
OUTPUT may be a product or service.
11

12. PRODUCTIVITY may be defined as follows:
MATHEMATICALLY:
PRODUCTIVITY = [OUTPUT / INPUT]
THUS:
PRODUCTIVITY measures the extent to which a
certain OUTPUT can be extracted FROM A
GIVEN INPUT.
It may be noted that PRODUCTION ( which is
number of products) is different from
PRODUCTIVITY.
12

13. • WORK STUDY IS A TOOL OF
PRODUCTIVITY ENHANCEMENT.
• It simplifies a job
TO REDUCE
UNNECESSARY OR EXCESS
WORK,
WASTEFUL USE OF RESOURCES
and sets up STANDARD TIME for
performing that job. 13

14. THIS IMPLIES THAT :
• THERE IS A DIRECT
RELATIONSHIP BETWEEN WORK
STUDY AND PRODUCTIVITY.
• THUS, BY APPLYING WS
PRINCIPLES IF THE COST IS
REDUCED BY 20%, THEN, WE CAN
SAY THAT PRODUCTIVITY HAS
GONE UP BY 20%. 14

15. WORK CONTENT OF A JOB
“WORK CONTENT”
• It means the amount of work contained in a
given job/work/product/process.
• It is measured in MAN-HOURS/ WORK-
HOURS (effort or labor of ONE person for ONE
hour), or MACHINE HOURS (running of a
machine/plant for ONE hour).
15

16. TOTAL TIME OF A JOB
‘TOTAL TIME OFA JOB’ COMPRISES OF:
1. BASIC WORK CONTENT &
2. EXCESS WORK CONTENT
BASIC WORK CONTENT is irreducible minimum time
required theoretically to produce one unit of product
In REAL LIFE WORLD, actual operation times are
FAR MORE IN EXCESS due to the EXCESS WORK 16
CONTENT.

17. CONTD.
• EXCESS WORK CONTENT may be due
to following
THREE CATEGORIES of factors:
(i) A-category:
A1: POOR DESIGN & FREQUENT
DESIGN CHANGES
A2: WASTE OF MATERIALS
A3: INAPPROPRIATE QUALITY
STANDARDS
17

18. CONTD.
(ii) B-category
B1: POOR LAYOUT & POOR
UTILISATION OF SPACE
B2: INADEQUATE MATERIAL
HANDLING
B3: FREQUENT STOPPAGES AS
PRODUCTION CHANGES FROM
ONE PRODUCT TO ANOTHER
18

19. CONTD.
B4: INEFFECTIVE METHOD OF
WORK
B5: POOR PLANNING OF
INVENTORY
B6: FREQUENT BREAKDOWN
OF MACHINES AND
EQUIPMENT
19

20. iii) C-category
C1: ABSENTEEISM AND LATENESS
C2: POOR WORKMANSHIP, AND
C3: ACCIDENTS AND OCCUPATIONAL
HAZARDS
TOTAL TIME OF A JOB
= BASIC WORK CONTENT + EXCESS WORK CONTENT ( A + B +C )
(OR, TOTAL INEFFECTIVE TIME)
20

21. WORK STUDY ,THE APPROACH:
21

22. WS IS VALUABLE because
By carrying out its systematic
procedures,one can get results as
good as or even better than the less
systematic genius would have been
able to achieve in the past.
It is systematic both in the
investigation of the problem and in
the development of its solution.
22

23. CONTD.
• It raises productivity of the plant /unit
by simply reorganization of the work,
with either a nominal or no extra input.
It sets the performance standards on
which the effectiveness of the
production planning and control
depends.
23

24. CONTD.
It contributes to human safety by
providing safer methods of work, and
allows for better working conditions by
exposing the hazardous situations.
Its application starts providing savings
immediately, and continues till the
operation continues.
24

25. CONTD.
It is a tool that can be used every where, be it
industrial or non-industrial environment.
It is easy and relatively cheaper in its
application.
It is an excellent weapon for starting an attack
on the inefficient system.
• HOWEVER, WS SPECIALISTS SHOULD APPLY IT
TACTFULLY, SO THAT WORKERS REMAIN CO-
OPERATIVE WHILE STUDIES ARE CONDUCTED IN
THE PLANT. 25

26. TECHNIQUES OF WORK STUDY:
These are:
1. METHOD STUDY is the systematic recording and
critical examination of ways of doing things in
order to make improvements.
THUS it simplifies the job and develops more
economical method of doing it.
2.WORK MEASUREMENT is the application
of techniques designed to establish the time for a
qualified worker to carry out a task at a defined rate
of working.
THUS it determines how long it should take to carry
out the work. 26

27. BASIC PROCEDURE OF WS comprise of following
STEPS:
1.SELECT the job/task/process to be studied.
2.RECORD all the relevant data/facts about the
selected job.
3.EXAMINE the recorded facts critically by challenging
its purpose, place, sequence, person, and
method.
4.DEVELOP new methods,as alternative methods, of
doing the selected job.
5.EVALUATE results of different alternative solutions.
6.DEFINE the new method and present it to the
concerned people.
7.INSTAL the new method and provide training to
the concerned staff .
8.MAINTAIN the new standard practice and establish 27
control procedures.

28. ACCORDING TO BARNES:
Since Methods Engineering is a form of CREATIVE
PROBLEM SOLVING , THE GENERAL PROBLEM
SOLVING PROCESSES can be employed in WS also.
Accordingly, following FIVE STEPS can be used:
1.Problem definition : Statement of the purpose/goal
2. Analysis of the problem : Fact-recording no
evaluation
3.Search for possible solutions : Finding several
alternative
solutions.
4. Evaluation of alternatives : Examining which
alternative meets the goal/criteria most, in
order to evolve the preferred solution. &
28
5. Recommendation for action : Communicating the

29. METHOD STUDY & JOB SELECTION
29

30. STEP I : JOB/TASK/PROCESS SELECTION
It involves following considerations:
1. ECONOMIC CONSIDERATIONS
2. TECHNOLOGICAL
CONSIDERATIONS
3. HUMAN CONSIDERATIONS
30

31. Contd.
1.ECONOMIC CONSIDERATIONS
Cost effectiveness i.e. to check whether or not the
WS application would pay.
For this,
- key-profit giving/ costliest operations with
largest waste/scrap should be attacked first.
- bottleneck operations, repetitive operations,
repeated material handling operations should be
studied.
- For locating most important operations,
PARETO ANALYSIS could be used.
31

32. 2.TECHNICAL/TECHNOLOGICAL
CONSIDERATIONS
The analysis involves application
of WS for the selection of the
operations/processes where new
technology e.g. automation/
robotisation should be introduced.
32

33. 3.HUMAN CONSIDERATIONS
Analysis involves location of those
operations which present the
sources of dissatisfaction and/or
annoyance to the workers due to
fatigue or monotony or unsafe
environment or a work which is
clumsy in nature. 33

34. RECORDING THE FACTS :
DIAGRAMS & CHARTS
34

35. STEP II : RECORDING THE FACTS
Related to the existing process/ job ALL THE FACTS
should be recorded ACCURATELY.
TOOLS OF FACT-RECORDING are:
(A) CHARTS, which may be of two types:
(i) Based on SEQUENCE:
(a) Outline Process Chart
(b) Flow Process Chart
(c) Two-Handed Chart ( or Operation
Chart / Left Hand & Right Hand chart)
35

36. CONTD.
(ii ) Based on TIME scale:
(a) Multiple Activity Chart
(b) SIMO ( SImultaneous MOtion) Chart
(B) DIAGRAMS: which may be of the
following types:
Flow diagram, String Diagram, Travel Chart,
Cyclegraph, & Chronocyclegraph,
36

37. PROCESS CHART SYMBOLS
ASME has recommended FIVE standard symbols to be used on
Process Charts, given below:
1. OPERATION : Main steps of the
task /job involving modification /change.
2. INSPECTION: Checking quality / quantity.
3. TRANSPORTATION : For movement of
persons/materials.
4. DELAY (TEMPORARY) : For waiting time of
operators or materials.
5. STORAGE (PERMANENT DELAY)] : For
controlled storage involving authorized
issue/receipt of material etc.
NOTE: FOR TWO PARALLEL EVENTS, BOTH ARE
SHOWN IN ONE JOINT OR COMBINED SYMBOL: e. g.
operation & inspection ,jointly are shown 37
by symbol, indicated in the figure.

38. THE OUTLINE FLOW PROCESS
CHART
• It uses ONLY TWO SYMBOLS:
&
• It provides an OVERALL PICTURE of the
process / job / task.
• Primarily it is used to show the sequence of
operations & inspections for a
MANUFACTURING or an ASSEMBLY kind of
jobs.
38

39. FLOW PROCESSCHART
• It uses ALL THE FIVE SYMBOLS and provides the
total sum details of the process/job under study.
• A Flow Process chart may be of the following
types:
1.MAN-TYPE in which every symbol is
related to his/her activity only.
2.MATERIAL TYPE in which every symbol
is related to the material of the job
or a document (e.g. in offices) or a
machine/equipment.
• Data / information in a flow process chart are
recorded in specifically designed FORM, as given
in the TEXT BOOK / CLASS ROOM. 39

40. STEP III : CRITICAL EXAMINATION
The facts recorded in the Flow Process
Chart are now EXAMINED CRITICALLY
by applying the
QUESTIONING TECHNIQUE,
which involves the following
SEQUENCE: 40

41. CONTD.
• PURPOSE for which the activity is done
• PLACE at ,, ,, ,, ,, ,,
• SEQUENCE in ,, ,, ,, ,, ,,
• PERSON by whom ,, ,, ,, ,, ,,
• MEANS by which ,, ,, ,, ,, ,,
WITH THE OBJECTIVE OF ELIMINATING/
COMBINING/ REARRANGING/ SIMPLIFYING
THE ACTIVITIES INVOLVED IN THE PROCESS.
QUESTIONING TECHNIQUE involves
1. PRIMARY QUESTIONS and
41
2. SECONDARY QUESTIONS explained below:

42. PRIMARY QUESTIONS
According to the QUESTIONING TECHNIQUE the PRIMARY
QUESTIONS are as follows:
• Purpose-based: WHAT is actually done?
WHY is the activity ELIMINATE
necessary, at all?
• Place-based: WHERE is it being done?
WHY at this place?
• Sequence-based: WHEN is it done?
WHY at that time? COMBINE or
• Person-based: WHO is doing it ? REARRANGE
WHY by this person?
• Means-based: HOW is it being done? SIMPLIFY
42
WHY in that particular way?

43. SECONDARY QUESTIONS
• Corresponding to each answer
obtained through the PRIMARY
QUESTIONS further questions are
raised to explore about the
ALTERNATIVES
i. e. alternate purpose, place,
sequence, person & means.
This methodology makes use of the
SECONDARY QUESTIONS given
as follows: 43

44. Contd.
• WHAT ELSE might be done?
• WHERE ELSE might it be done?
• WHEN ELSE might it be done?
• WHO ELSE might do it? &
• HOW ELSE might it be done?
BY ANSWERING THE PRIMARY &
SECONDARY QUESTIONS WE USE THE
SYSTEMATIC CRITICAL EXAMINATION IN
ORDER TO EVOLVE A BETTER METHOD OF
44
DOING THE WORK.

45. Contd.
AS A RESULT, ONE CAN DEVELOP A
BETTER METHOD IN LIGHT OF THE
OBTAINED ANSWERS TO THE FOLLOWING
QUESTIONS:
• WHAT should be done?
• WHERE should it be done?
• WHEN should it be done?
• WHO should do it ?
45
• HOW should it be done?

46. LECTURE : 15-17
CHAPTER : 8
RECORDING MOVEMENT OF
WORKERS/MATERIALS
46

47. RECORDINGMOVEMENT OF WORKERS/
MATERIALS
TOOLS USED FOR THIS PURPOSE ARE:
• STRING DIAGRAM
• FLOW DIAGRAM
• TRAVEL CHART
47

48. STRING DIAGRAM
• IT IS A SCALE PLAN OR MODEL ON WHICH
A THREAD OR STRING IS USED TO TRACE
AND MEASURE THE PATH OF WORKERS/
MATERIALS DURING A SPECIFIED
SEQUENCE OF EVENTS.
• LENGTH OF THE THREAD/STRING
MEASURES THE DISTANCE MOVED.
48

49. FLOW DIAGRAM
• It is a FLOOR-PLAN showing the path of
travel of the operator or the material,
through the plant.
• It ALSO indicates the direction of travel by
means of arrows, drawn on the diagram.
49

50. TRAVEL CHART ( or, FROM-TO CHART)
• It is a tabular record of quantitative data about
movement of workers/materials/equipment between
any number of places over a given period of time. It is
always in the form of a SQUIRE, having within it the
squires.
EACH SMALL SQUIRE REPRESENTS A STATION.
Along the TOP, squires from left to right represent the
stations FROM where movement or travel occurs.
Along those DOWN THE LEFT HAND, the squires
represent the stations TO which the movement is
made.
50

51. MAN-MACHINE CHART
(MULTIPLE ACTIVITY CHART)
• This kind of process chart records the activities of
the operator as well as the machine on the same
chart against a common time scale.
• Separate vertical columns ( in the form of bars)
are used for both.
• The chart clearly indicates the IDLENESS (or
UTILISATION) of operator as well as the machine.
• On the basis of the recorded events in the chart,
one can rearrange the process so that IDLE-TIME
is reduced, or BETTER UTILISATION of the
operator/machine is achieved.
• It is used for balancing the work between man
and machine ;proper utilization of maintenance
crew /team-activities in mass production. 51

52. METHODS & MOVEMENTS AT THE
WORKPLACE
52

53. METHODS & MOVEMENTS AT THE
WORKPLACE
PRINCIPLES OF MOTION ECONOMY
These principles can be helpful in work design, in
reducing the human fatigue and in improving the
work efficiency. According to Barnes, these can be
presented under following THREE subgroups:
1.Principles of motion economy as related to the
USE OF HUMAN BODY
2.Principles of motion economy as related to the
ARRANGEMENT OF THE WORKPLACE
3.Principles of motion economy as related to the
DESIGN OF TOOLS & EQUIPMENT 53

54. [A] .Principles of motion economy as related to
the USE OF HUMAN BODY
• 1.The two hands should begin and
complete their movements at the same
time.
• 2. The two hands should not be idle at the
same time.
• 3.Motions of the arms should be
symmetrical and in opposite direction
and should be made simultaneously.
54

55. Principles: Contd
• 4.Hand and body motions should be made at
the lowest classification at which it is possible
to do the work satisfactorily.
[The term ‘CLASSIFICATION OF HAND
MOTION’ is explained as follows]
55

56. CLASSIFICATION OF HAND MOTIONS
CLASS PIVOT BODY MEMBERS MOVED
1 Knuckle Finger (F)
2 Wrist Hand (H) + F
3 Elbow Fore Arm (FA) + H + F
4 Shoulder Upper Arm (UA) +FA+H+F
5 Trunk Torso + UA + FA + H + F
56

57. Principles : CONTD.
• 5. Momentum should be employed to help the
worker ,but should be reduced to a minimum
whenever it is to overcome by muscular effort.
• 6.Continuous curved motions are to be
preferred to straight line motion involving
sudden and sharp changes in direction.
• 7. Ballistic (free-swinging) motions are
faster, easier, and more accurate than
restricted or controlled motions. 57

58. .
Principles CONTD
• 8.Rhythm is essential to the smooth and
automatic performance of a repetitive
operation. The work should be arranged to
permit an easy and natural rhythm whenever it
is possible.
• 9.Work should be arranged so that eye-
movements are confined to a comfortable
area, without the need for frequent changes of
the focus.
58

59. [B].Principles of motion economy as related
to the ARRANGEMENT OF THE WORKPLACE
1.Definite and fixed positions/stations
should be provided for all tools and
materials to permit habit formation.
2.Tools and materials should be pre-
positioned to reduce searching.
59

60. 3.Gravity-feed, bins and containers should be
used to deliver the materials as close to the
point of use as possible.
• 4.Tools, materials, and controls should be
located within the ‘maximum working area’
and as near to the worker as possible.
[WORKING AREA (WA) may be divided into:
1.NORMAL WA &
2.MAXIMUM WA explained below ]
60

61. Normal Working Area (WA) : Cotd.
( Finger + wrist + elbow) Movement
MOST CONVENIENT ZONE
Edge
of bench operator
operator
61
Maximum WA : (Shoulder Movement)

62. DIMENSIONS FOR SEATED TASKS
• 1.SEAT HEIGHT should be adjustable :
( range:36-45 )
• 2. WORK SURFACE HEIGHT should be around
elbow level (range:65-72 cm)
• 3.LEG CLEARANCE : 40 cm at knee level
& 60 cm for the feet
• 4.THIGH CLEARANCE : 20 cm minimum
• 5.WORK SURFACE THICKNESS : 5cm max.
62

63. 5.Materials and tools should be arranged to
permit the best sequence of motions.
6.‘Drop deliveries’ or ejectors should be used
wherever possible, so that operators do not
have to use his/her hands to dispose of the
finished work.
63

64. 7.Provision should be made for adequate
lighting and, a chair of the type of height to
permit good posture should be provided.
The height of the workplace and seat should
be arranged to allow alternate standing and
sitting.
8.The color of the workplace should contrast
with that of the work and thus reduce the
eye-fatigue.
64

65. [C]. Principles of motion economy as related to the
the DESIGN OF TOOLS & EQUIPMENT
1.The hands should be relieved of all work of
“holding” the work-piece where this can be
done by a jig, fixture or foot-operated
device.
2.Two or more tools should be combined
wherever possible.
3.Where each finger performs some specific
movement, as in typewriting, the load
should be distributed in accordance with the
inherent capacities of the fingers.
65

66. 4.Handles such as those on cranks and large
screw divers should be so designed that as
much surface of the hand as possible can
come in contact with the handle. This is
specially necessary when considerable force
has to be used on the handle.
5.Levers crossbars and hand-wheels should be
so placed that the operator can use them with
the least change in body position and the
largest mechanical advantage. 66

67. TWO-HANDED PROCESS CHART (OPERATION
CHART/LEFT-HAND RIGHT-HAND CHART)
• It shows the activities of the two hands in
relation to one another.
ACCORDING TO BARNES:
• It uses ONLY TWO SYMBOLS: &
Small circle for TRANSPORTATION
& Big circle for OPERATION.
ACCORDING TO ILO :
• It uses ALL process chart symbols EXCEPT
INSPECTION
• After studying a few cycles recording is done.
• ONLY ONE HAND is charted AT A TIME. 67

68. FUNDAMENTAL HAND MOTIONS
• Gilbreth observed that most work done
by two hands consists of a few
fundamental motions.
• He called EACH ONE of them as
THERBLIG. (name of GILBRETH ,read in
reverse order).
THERBLIG : GILBRETH
( read in reverse order)
68

69. contd.
• Today we have 17 Therbligs as follows:
Search, select, grasp,
transport empty, transport loaded,
hold, release load
position, preposition, inspect,
assemble, disassemble, use,
unavoidable delay avoidable delay,
plan, & rest for overcoming
fatigue.
• THESE ARE USED IN MICROMOTION
STUDIES (FACTS RECORDED ON FILMS)
69

70. MICROMOTION STUDIES
• Operations with very short cycles &
repetitive cycles need greater details to
analyze it for saving motions and
effort( i.e. planning for lesser fatigue).
This goal can be achieved through
Micro-motion Studies.
• MICRO means ‘small. Thus here we
study the motions in terms of
THERBLIGS.
70

71. CONTD.
• Such a study involves the use of
FILM and VIDEO
when operator performs the job.
• Later on the film/video can be run slowly
THROUGH A PROJECTOR and
• ‘Frame by frame’ analysis of the work
can be carried out.
• Film provides greater flexibility of filming
and playback speeds WHEREAS video is
easier in use. 71

72. Contd.
STEPS:
1. Filming the job
2. Analysis of the film, &
3. Presenting DATA/FACTS
graphically through
SIMO chart.
(SImultaneous Motion Chart)
72

73. CONTD.
• EQUIPMENT:
Camera, Film, Micro-chronometer,
Exposure meter, Flood lights,
Reflectors, Tripod,, Projector etc.
OR,
VIDEOCAMERA plus its
accessories for filming
operation.
73

74. CONTD.
ADVANTAGES OF MICROMOTION STUDIES
OVER DIRECT OBSERVATION.
• Greater details are made availalble
• More accurate
• Easier in data collection
• Better for record keeping
• Help in work study personnel's
development 74

75. FILM ANALYSIS:
• Film is run on projector,
• Details of the work-cycle are identified in
terms of THERBLIGS, first for
Left hand
and then for
Right hand,
• TIME ( in WINK) is noted from the
Chronometer readings of the film for each
therblig.
[1 WINK = (1/2000) OF A MINUTE 75 ]

76. CONTD.
With these data SIMO (Simultaneous
Motion) chart is made as shown
below :
LH Activities Therblig Time Therblig RH Activity
76

77. MEMOMOTION ANALYSIS
• It was introduced by MUNDEL.
• It is a special type of micro-motion study in
which activities are FILMED AT MUCH
SLOWER SPEED (60 to 100 frames per
minute) i.e. at longer intervals than normal
(intervals being between 0.5 to 4 s).
• Thus a general pattern of movements can
be obtained and avoidable motions can be
identified.
77

78. • STEPS:
 Study the operation to be filmed
 Prepare the film
 Analyze the film
 Develop a better method.
• ADVANTAGES:
More economical (less film consumed) and Long
sequence of activities can be recorded;
• APPLICATIONS:
Team-work studies ;
Material flow studies
( e.g. baggage movement at the airports )
Long cycle job studies &
78
Study of artificial limbs’ motions etc

79. CYCLEGRAPH
• It was introduced by Gilbreth.
• It is a photographic record of the path of
movement of the operator doing a job.
• Little source of light (bulb) is attached to the
hand or finger or any other body part, whose
motions are to be analyzed. When he/she
performs the operation and photograph is
taken continuously, the path of motions is
recorded on the film as CONTINUOUS
STREAK OF LIGHT as shown below
OPERATO R
79

80. CHRONOCYCLEGRAPH
• It is a special type of cycle-graph in which the light
source (bulb) is suitably INTERRUPTED ELECTRICALLY
so that the path of motion in the photograph appears as
a SERIES OF PEAR-SHAPED SPOTS instead of
continuous streak of light as shown below
PEAR-SHAPED SPOTS
MOTION DIRECTION
• The pointed end of the pear shows the direction of movement.
• More elongated and spaced pear-spots indicate higher speed of
operation..
• It helps in studying the complex and restricted motions also. 80