Consider a bus which is travelling at 100 km/h in a south east
direction.
A good way of representing this situation is to use an arrow
on a scale diagram.
Thelength of the arrowrepresents the size or magnitude of
the velocity and thearrowheadshows the direction of travel.
Scale: 1 cm represents 50 km/h
Consider the vector represented by the line segment from O to A.
² Thisvectorcould be represented by
¡!
OA or a
bold used
in text books
or a.
used by
students
² Themagnitudeorlengthcould be represented by
j
¡!
OAj or OA or jaj or jaj.
For we say that
¡!
AB is the vector whichemanatesfrom A and
terminatesat B, and that
¡!
AB is theposition vectorof B
relative to A.
Example 1 Self Tutor
On a scale diagram, sketch the vector which representsa velocity of:
a 15 m/s in a westerly direction b 40 m/s on a bearing 075 o.
a Scale: 1 cm ́ 10 m/s b Scale: 1 cm ́ 10 m/s
EXERCISE 24A
1 Using a scale of 1 cm represents 10 units, sketch a vector to represent:
a 40 km/h in a SW direction
b 35 m/s in a northerly direction
c a displacement of 25 m in a direction 120 o
d an aeroplane taking off at an angle of 12 oto the runway with a speed of 60 m/s.
DIRECTED LINE SEGMENT REPRESENTATION
[5.1, 5.3]
A
45°
N
WE
S SE
a
O
A
A
B
N
S
W E
N
75° 40 m/s
15 m/s
~
~
484 Vectors (Chapter 24)
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Y:\HAESE\IGCSE01\IG01_24\484IGCSE01_24.CDR Thursday, 20 November 2008 4:01:09 PM PETER