physical quantities matriculation stpm
TRANSCRIPT
-
7/28/2019 Physical quantities Matriculation STPM
1/58
1
PHYSICS CHAPTER 1
CHAPTER 1:CHAPTER 1:
Physical quantities andPhysical quantities and
measurementsmeasurements
(3 Hours)(3 Hours)
www.kms
.matrik.e
du
.my/physics
www.kms
.matrik.e
du
.my/physic
s
-
7/28/2019 Physical quantities Matriculation STPM
2/58
PHYSICS CHAPTER 1
2
At the end of this chapter, students should be able to:At the end of this chapter, students should be able to: StateState basic quantities and their respective SI units: lengthbasic quantities and their respective SI units: length
(m), time (s), mass (kg), electrical current (A), temperature(m), time (s), mass (kg), electrical current (A), temperature(K), amount of substance (mol) and luminosity (cd).(K), amount of substance (mol) and luminosity (cd).
StateState derived quantities and their respective units andderived quantities and their respective units andsymbols: velocity (m ssymbols: velocity (m s-1-1), acceleration (m s), acceleration (m s-2-2), work (J),), work (J),force (N), pressure (Pa), energy (J), power (W) andforce (N), pressure (Pa), energy (J), power (W) andfrequency (Hz).frequency (Hz).
StateState and convert units with common SI prefixes.and convert units with common SI prefixes.
Learning Outcome:
1.1 Physical Quantities and Units (1 hour)
www.kms
.matrik.e
du
.my/physics
www.kms
.matrik.e
du
.my/physic
s
-
7/28/2019 Physical quantities Matriculation STPM
3/58
PHYSICS CHAPTER 1
3
Physical quantityPhysical quantity is defined as a quantity which can be measuredquantity which can be measured
using measuring instrument.using measuring instrument.
It can be categorised into 2 types
Basic (base) quantityBasic (base) quantity
Derived quantityDerived quantity
Basic quantityBasic quantity is defined as a quantity which cannot be derivedquantity which cannot be derived
from any other physical quantity.from any other physical quantity.
Table 1.1 shows all the basic (base) quantities.
1.1 Physical Quantities and Units
Quantity Symbol SI Unit Symbol
Length l metre m
Mass m kilogram kg
Time t second s
Temperature T/ kelvin K
Electric current I ampere A
Amount of substance N mole mol
Luminous Intensity candela cdTable 1.1Table 1.1
-
7/28/2019 Physical quantities Matriculation STPM
4/58
PHYSICS CHAPTER 1
4
Derived quantity Symbol Formulae Unit
Velocity v s/t m s-1
Frequency f 1/T s-1 or Hz (hertz)
Acceleration a v/t m s-2
Pressure F/A N m-2 or Pa
(pascal)
Momentum p m v kg m s-1
Force F m a kg m s-2 or
N(newton)
Work W F s kg m2 s-2 or
J(joule)
Power P W/t
Js-1 or W (watt)
Table 1.2Table 1.2
Derived quantityDerived quantity is defined as a quantity that is obtained from thequantity that is obtained from the
combination of base quantities.combination of base quantities.
Table 1.2 shows some examples of derived quantity.
-
7/28/2019 Physical quantities Matriculation STPM
5/58
PHYSICS CHAPTER 1
5
UnitUnit is defined as a standard size of measurement of aa standard size of measurement of a
physical quantity.physical quantity. Examples :
1 second1 second is defined as the time required forthe time required for
9,192,631,770 vibrations of radiation emitted by a9,192,631,770 vibrations of radiation emitted by a
caesium-133 atom.caesium-133 atom.
1 kilogram1 kilogram is defined as the mass of a platinum-iridiumthe mass of a platinum-iridiumcylinder kept at International Bureau of Weights andcylinder kept at International Bureau of Weights and
Measures ParisMeasures Paris.
1 meter1 meter is defined as the length of the path travelled bythe length of the path travelled by
light in vacuum during a time interval oflight in vacuum during a time interval of
1299, 792, 458
s
-
7/28/2019 Physical quantities Matriculation STPM
6/58
PHYSICS CHAPTER 1
6
rad = 180o
1 rad =180
o
=57.296o
The unit of a basic quantity is called base unit.
additional unit for base unit: unit of plane angle - radian (rd)
unit of solid angle- steradian (sr)
The common system of units used today are S.I unit (S.I unit (SystemSystem
International/metric systemInternational/metric system)) and cgs unit - UK.
The unit of derived quantity called derived unit
-
7/28/2019 Physical quantities Matriculation STPM
7/58
PHYSICS CHAPTER 1
7
It is used for represent larger and smaller values.for represent larger and smaller values.
Table 1.3 shows all the unit prefixes.
Examples:
5740000 m = 5740 km = 5.74 Mm
0.00000233 s = 2.33 106 s = 2.33 s
Prefix Multiple Symbol
tera 1012 T
giga 109 G
mega 106
Mkilo 103 k
deci 101 d
centi 102 c
milli 103 m
micro 106
nano 109 n
pico 1012 p
1.1.1 Unit Prefixes
Table 1.3Table 1.3
-
7/28/2019 Physical quantities Matriculation STPM
8/58
PHYSICS CHAPTER 1
8
Table 1.4 shows the conversion factors between SI and British units for
length and mass only.
1.1.2 Conversion of Unit
Length Mass
1 m = 39.37 in = 3.281 ft 1 kg = 103 g
1 in = 2.54 cm 1 slug = 14.59 kg1 km = 0.621 mi 1 lb = 0.453 592 kg
1 mi = 5280 ft = 1.609 km 1 kg = 0.0685 slug
1 angstrom ( ) = 10 10 m
Table 1.4Table 1.4
-
7/28/2019 Physical quantities Matriculation STPM
9/58
PHYSICS CHAPTER 1
9
Solve the following problems of unit conversion.
a. 15 mm2 = ? m2 b. 65 km h1 = ? m s1
c. 450 g cm3 = ? kg m3 d. 29 cm = ? in
e. 12 mi h1 = ? m s1
Solution :Solution :
a. 15 mm2
= ? m2
b. 65 km h-1 = ? m s-1
11stst method :method : 65 km h1=
65103 m1 h
Example 1.1 :
1 mm 2=103m 2
-
7/28/2019 Physical quantities Matriculation STPM
10/58
PHYSICS CHAPTER 1
10
22ndnd method :method :
c. 450 g cm-3 = ? kg m-3
65 km h1=65 km1 h
450 g cm3=450 g1 cm 3 103 kg
1 g
1 cm 3
102
3
m
3
-
7/28/2019 Physical quantities Matriculation STPM
11/58
PHYSICS CHAPTER 1
11
d. 29 cm = ? in
e. 12 mi h-1 = ? m s-1
29 cm=29 cm
1
2 .54
in
1 cm 12 mi h1=
12 mi1 h
1 . 609 km1 mi
1000 m1 km
1 h3600 s
-
7/28/2019 Physical quantities Matriculation STPM
12/58
PHYSICS CHAPTER 1
12
At the end of this chapter, students should be able to:At the end of this chapter, students should be able to: DefineDefine scalar and vector quantities.scalar and vector quantities. PerformPerform vector addition and subtraction operationsvector addition and subtraction operations
graphically:graphically: commutative rulecommutative rule associative rule, andassociative rule, and distributive ruledistributive rule
Resolve vectorResolve vectorinto two perpendicular components (2-D) :into two perpendicular components (2-D) :
Components in the x and y axes.Components in the x and y axes.
Components in the unit vectors in CartesianComponents in the unit vectors in Cartesiancoordinate.coordinate.
Learning Outcome:
1.2 Scalars and Vectors (2 hours)
i , jwww.kms
.matrik.e
du
.my/physic
s
www.kms
.matrik.e
du
.my/physic
s
-
7/28/2019 Physical quantities Matriculation STPM
13/58
PHYSICS CHAPTER 1
13
At the end of this topic, students should be able to:At the end of this topic, students should be able to: Define and useDefine and use dot (scalar) product:dot (scalar) product:
and cross (vector) product:and cross (vector) product:
Direction determined by corkscrew method or right handDirection determined by corkscrew method or right handrule.rule.
Learning Outcome:
1.2 Scalars and Vectors (2 hours)
AB=A B cos=B A cos
AB=A B sin =B A sinwww.kms
.matrik.e
du
.my/physic
s
www.kms
.matrik.e
du
.my/physic
s
-
7/28/2019 Physical quantities Matriculation STPM
14/58
PHYSICS CHAPTER 1
14
ScalarScalarquantity is defined as a quantity with magnitudequantity with magnitude only. e.g. mass, time, temperature, pressure, electric current,
work, energy and etc.
Mathematics operation: ordinary algebra
VectorVectorquantityis defined as a quantity with both magnitudequantity with both magnitude
& direction.& direction.
e.g. displacement, velocity, acceleration, force, momentum,
electric field, magnetic field and etc.
Mathematics operation: vector algebra
1.2 Scalars and Vectors
-
7/28/2019 Physical quantities Matriculation STPM
15/58
PHYSICS CHAPTER 1
15
Table 1.6 shows written form (notation) of vectors.
Notation of magnitude of vectors.
1.2.1 Vectors
Vector ALengthLength of an arrow magnitudemagnitude of vector A
displacement velocity acceleration
s v as av
v=v
a=a
s (bold) v (bold) a (bold)
DirectionDirection of arrow directiondirection of vector A
Table 1.6Table 1.6
-
7/28/2019 Physical quantities Matriculation STPM
16/58
-
7/28/2019 Physical quantities Matriculation STPM
17/58
PHYSICS CHAPTER 1
17
Can be represented by using:
a)a) Direction of compassDirection of compass, i.e east, west, north, south, north-east,
north-west, south-east and south-west
b)b) Angle with a reference lineAngle with a reference line
e.g. A boy throws a stone at a velocity of 20 m s-1, 50 above
horizontal.
1.2.2 Direction of Vectors
50
v
x
y
0
-
7/28/2019 Physical quantities Matriculation STPM
18/58
PHYSICS CHAPTER 1
18
c)c) CartesianCartesian coordinates
2-Dimension (2-D)
s=x , y =1 m, 5 m
s
y/m
x/m
5
10
-
7/28/2019 Physical quantities Matriculation STPM
19/58
PHYSICS CHAPTER 1
19
3-Dimension (3-D)
s
2
3
4
s=x , y , z=4, 3, 2 my/m
x/m
z/m
0
-
7/28/2019 Physical quantities Matriculation STPM
20/58
PHYSICS CHAPTER 1
20
d)d) PolarPolarcoordinates
e)e) DenotesDenotes with + or signs+ or signs.
F=30 N,150
F150
+
+-
-
-
7/28/2019 Physical quantities Matriculation STPM
21/58
PHYSICS CHAPTER 1
21
There are two methods involved in addition of vectors graphically i.e.
ParallelogramParallelogram TriangleTriangle
For example :
1.2.3 Addition of Vectors
ParallelogramParallelogram TriangleTriangle
BA
B
A
AB
O
AB
B
A
AB
O
-
7/28/2019 Physical quantities Matriculation STPM
22/58
PHYSICS CHAPTER 1
22
Triangle of vectors method:
a) Use a suitable scale to draw vector A.
b) From the head of vector A draw a line to represent the vector B.
c) Complete the triangle. Draw a line from the tail of vector A to the
head of vector B to represent the vectorA + B.
A
B=
B
A
Commutative RuleCommutative Rule
B
A
BAO
-
7/28/2019 Physical quantities Matriculation STPM
23/58
PHYSICS CHAPTER 1
23
If there are more than 2 vectors therefore
Use vector polygon and associative rule. E.g. PQR
RQP
R
Q
P PQ
P
Q
R=
P
Q
R Associative RuleAssociative Rule
PQ R
-
7/28/2019 Physical quantities Matriculation STPM
24/58
PHYSICS CHAPTER 1
24
Distributive Rule :
a.
b.
For example :
Proof of case a:Proof of case a: let = 2
AB = A BA= AA
, are real number
AB =2 AB
B
A
AB
O 2 AB
-
7/28/2019 Physical quantities Matriculation STPM
25/58
PHYSICS CHAPTER 1
25
2 AO
2 B
2 A2 B
2 AB =2 A2 B
A B=2 A2 B
-
7/28/2019 Physical quantities Matriculation STPM
26/58
PHYSICS CHAPTER 1
26
Proof of case b:Proof of case b: let = 2 and = 1
A
A= 21 A=3 A
3 A
AA=2 A1 A2 A A
3 A
=
21 A=2 A1 A
-
7/28/2019 Physical quantities Matriculation STPM
27/58
PHYSICS CHAPTER 1
27
For example :
1.2.4 Subtraction of Vectors
ParallelogramParallelogram TriangleTriangle
DC
O
C D
O
D
C D=C D C
D
C
D
C
DC
D
-
7/28/2019 Physical quantities Matriculation STPM
28/58
PHYSICS CHAPTER 1
28
Vectors subtraction can be used
to determine the velocity of one object relative to another object
i.e. to determine the relative velocity. to determine the change in velocity of a moving object.
1. Vector A has a magnitude of 8.00 units and 45 above the positive x
axis. Vector B also has a magnitude of 8.00 units and is directed alongthe negative x axis. Using graphical methods and suitable scale to
determine
a) b)
c) d)(Hint : use 1 cm = 2.00 units)
Exercise 1.2 :
AB AB
A2
B 2
A
B
-
7/28/2019 Physical quantities Matriculation STPM
29/58
PHYSICS CHAPTER 1
29
11stst methodmethod :
1.2.5 Resolving a Vector
R
Ry
Rx
0x
y
Rx
R=cos Rx= R cos
Ry
R=sin Ry= R sin
22ndnd methodmethod :
R
Ry
Rx
0x
y
Rx
R=sin Rx= R sin
Ry
R=cos R
y= R cos
-
7/28/2019 Physical quantities Matriculation STPM
30/58
PHYSICS CHAPTER 1
30
The magnitude of vectormagnitude of vectorR :
Direction of vectorDirection of vectorR :
VectorR in terms of unit vectors written as
R orR=Rx 2Ry 2
tan=R
y
Rx
or=tan1RyR
x
R=RxiR
yj
-
7/28/2019 Physical quantities Matriculation STPM
31/58
PHYSICS CHAPTER 1
31
A car moves at a velocity of 50 m s-1 in a direction north 30 east.
Calculate the component of the velocitya) due north. b) due east.
Solution :Solution :
Example 1.6 :
N
EW
S
vN
vE
v30
60
a)
b)
vN= v cos30
orvN= v sin60
vE= v sin30
or
vE= v cos60
-
7/28/2019 Physical quantities Matriculation STPM
32/58
PHYSICS CHAPTER 1
32
A particle S experienced a force of 100 N as shown in figure above.
Determine the x-component and the y-component of the force.
Solution :Solution :
Example 1.7 :
150
F
Sx
15030
F
Sx
y
Fy
Fx
Vector x-component y-component
Fx=Fcos30
orFFx=Fcos150
Fy=Fsin 30
Fy=Fsin150
-
7/28/2019 Physical quantities Matriculation STPM
33/58
PHYSICS CHAPTER 1
33
The figure above shows three forces F1, F2and F3 acted on a particle O.
Calculate the magnitude and direction of the resultant force on particle
O.
Example 1.8 : y
30o
O
F230N
F110N
30o x
F340N
-
7/28/2019 Physical quantities Matriculation STPM
34/58
PHYSICS CHAPTER 1
34
30o
Solution :Solution :
O
y
x
F3
30
o
F3y
Fr= F=F1F2F3Fr= Fx Fy
Fx=F1xF2xF3x
Fy=F1yF2yF3y
F2x
F1
F2
60o
F2
F3x
-
7/28/2019 Physical quantities Matriculation STPM
35/58
PHYSICS CHAPTER 1
35
Solution :Solution :
Vector x-component y-component
F1
F3
F2
F1x=0 NF
1y=F
1F
1y=10 N
F2x=30cos60
F2x=15 N F
2y=30sin60
F2y=26 N
F3x=40cos30
F3x=34 .6 N
F3y=40sin30
F3y=20 N
VectorVector
sumsum
-
7/28/2019 Physical quantities Matriculation STPM
36/58
PHYSICS CHAPTER 1
36
y
xO
Solution :Solution :
The magnitude of the resultant force is
and
Its direction is 162162 from positive x-axis OR 18from positive x-axis OR 18 above negative x-axis.above negative x-axis.
Fr=Fx
2Fy2
=tan1FyFx
Fy
Fx
162
Fr
18
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
37/58
PHYSICS CHAPTER 1
37
1. Vector has componentsAx = 1.30 cm,Ay = 2.25 cm; vector
has componentsBx = 4.10 cm,By = -3.75 cm. Determine
a) the components of the vector sum ,
b) the magnitude and direction of ,
c) the components of the vector ,
d) the magnitude and direction of . (Young & freedman,pg.35,no.1.42)
ANS. : 5.40 cm, -1.50 cm; 5.60 cm, 345ANS. : 5.40 cm, -1.50 cm; 5.60 cm, 345; 2.80 cm, -6.00 cm;; 2.80 cm, -6.00 cm;6.62 cm, 2956.62 cm, 295
2. For the vectors and in Figure 1.2, use the method of vector
resolution to determine the magnitude and direction of
a) the vector sum ,
b) the vector sum ,
c) the vector difference ,
d) the vector difference .(Young & freedman,pg.35,no.1.39)
ANS. : 11.1 m sANS. : 11.1 m s-1-1, 77.6, 77.6; U think;; U think;28.5 m s28.5 m s-1-1, 202, 202; 28.5 m s; 28.5 m s-1-1, 22.2, 22.2
Exercise 1.3 :
AB
A
ABBABA
B
A B
AB
BAABBA
Figure 1.2Figure 1.2
y
x0
37.0
B 18 .0 m s-1
A 12 .0 m s-1
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
38/58
PHYSICS CHAPTER 1
38
3. Vector points in the negativex direction. Vector points at an
angle of 30 above the positivex axis. Vector has a magnitude of
15 m and points in a direction 40 below the positivex axis. Giventhat , determine the magnitudes of and .(Walker,pg.78,no. 65)
ANS. : 28 m; 19 mANS. : 28 m; 19 m
4. Given three vectorsP,Q andR as shown in Figure 1.3.
Calculate the resultant vector ofP,Q andR.
ANS. : 49.4 m sANS. : 49.4 m s22; 70.1; 70.1 above + x-axisabove + x-axis
Exercise 1.3 :
C
A
BABC=0 A
B
Figure 1.3Figure 1.3
y
x0
50R 10 m s2
P35 m s2 Q 24 m s2
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
39/58
PHYSICS CHAPTER 1
39
notations
E.g. unit vectora a vector with a magnitude of 1 unit in the direction
of vectorA.
Unit vectors are dimensionless.
Unit vector for 3 dimension axes :
1.2.6 Unit Vectors
A
a
a ,b , c
a=
A
A=1
[ a ]=1
y axis j @ j bold i=j=k=1xaxis i@ i bold
z axisk @ kbold
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
40/58
PHYSICS CHAPTER 1
40
Vector can be written in term of unit vectors as :
Magnitude of vector,
x
z
y
kji
r=rx iry jrzk
r=rx 2 ry 2rz 2
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
41/58
PHYSICS CHAPTER 1
41
E.g. : s=4 i3 j2 k m
3 j
x/m
y/m
z/m
0
s4 i2 k
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
42/58
PHYSICS CHAPTER 1
42
Two vectors are given as:
Calculate
a) the vector and its magnitude,
b) the vector and its magnitude,
c) the vector and its magnitude.
Solution :Solution :
a)
The magnitude,
Example 1.9 :
ba
a=i2 j6 k m
ab
b=4 i3 j k m
abx=axbx=14=5 iab
y
=ay
by
=23=5 j
abz=azbz=61=7 k
2ab
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
43/58
PHYSICS CHAPTER 1
43
b)
The magnitude,
c)
The magnitude,
bax=bxax=41=3 i
ba y=byay=3 2 =jba z=bzaz=16=5 k
2ab x=2axbx=2 1 4=6 i
2ab y=2ayby=2 2 3 =7 j2abz=2azbz=2 6 1=13 k
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
44/58
PHYSICS CHAPTER 1
44
Scalar (dot) productScalar (dot) product
The physical meaning of the scalar productphysical meaning of the scalar productcan be explained by
considering two vectors and as shown in Figure 1.4a.
Figure 1.4b shows the projection of vector onto the direction of
vector .
Figure 1.4c shows the projection of vector onto the direction of
vector .
1.2.7 Multiplication of Vectors
A B
A
B
AB
Figure 1.4aFigure 1.4a
A
BA
B
B cos
Figure 1.4bFigure 1.4b
A
BAcosFigure 1.4cFigure 1.4c
( )BABBA
toparallelofcomponent=
( )ABABA
toparallelofcomponent=
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
45/58
PHYSICS CHAPTER 1
45
From the Figure 1.4b, the scalar product can be defined as
meanwhile from the Figure 1.4c,
where
The scalar product is a scalar quantityscalar quantity.
The angle ranges from 0 to 180 . When
The scalar product obeys the commutative law of multiplicationcommutative law of multiplication i.e.
AB=A B cos
: angle between two vectors
BA=B A cos
090 scalar product is positivepositive
90180 scalar product is negativenegative
=90
scalar product is zerozero
AB=BA
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
46/58
PHYSICS CHAPTER 1
46
Example of scalar product is work donework done by a constant force where the
expression is given by
The scalar product of the unit vectors are shown below :W=Fs=Fscos =s Fcos
x
z
y
kji
ii=i2cos0o=12 1=1
ii=jj=kk=1
jj=j2cos0o=12 1 =1
kk=k2 cos0o=1 2
1 =1
ij= 1 1 cos 9 0o=0ij=jk=ik=0
ik= 1 1 cos 90
o
=0
jk= 1 1 cos 9 0o=0
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
47/58
PHYSICS CHAPTER 1
47
Calculate the and the angle between vectors and for the
following problems.a) b)
Solution :Solution :
a)
The magnitude of the vectors:
The angle ,
Example 1.10 :AAB B
AB= 1 4 ii1 2 jj1 3 kk
A=ik A=4 i3 jkB= 4 i2 j3 k B=2 j3 k
AB=423
AB=AB cos
=cos1 ABAB =cos1
3
329
ANS.:ANS.:3; 99.43; 99.4
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
48/58
PHYSICS CHAPTER 1
48
Referring to the vectors in Figure 1.5,a) determine the scalar product between them.
b) express the resultant vector ofCandD in unit vector.
Solution :Solution :
a) The angle between vectors
Cand
Dis
Therefore
Example 1.11 :
=18025 19=174
Figure 1.5Figure 1.5
y
x0
C1 m
D 2 m 19
25
CD=CD cos= 1 2cos174
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
49/58
PHYSICS CHAPTER 1
49
b) Vectors CandD in unit vector are
and
Hence
C=Cx
iCy
j
= 1cos25 i1sin25 j
C D= 0.911.89 i0.420.65 j
D=2cos19 i2sin19 j
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
50/58
PHYSICS CHAPTER 1
50
Vector (cross) productVector (cross) product
Consider two vectors :
In general, the vector product is defined as
and its magnitudemagnitude is given by
where
The angle ranges from 0 to 180 so the vector product always
positivepositive value. Vector product is a vector quantityvector quantity.
The direction of vector is determined by
B= p iq jrk
A=x iy jz k
AB=C
AB=C=ABsin=AB sin: angle between two vectors
RIGHT-HAND RULERIGHT-HAND RULE
C
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
51/58
PHYSICS CHAPTER 1
51
For example:
How to use right hand rule :
Point the 4 fingers to the direction of the 1st
vector. Swept the 4 fingers from the 1st vector towards the 2nd vector.
The thumb shows the direction of the vector product.
Direction of the vector product always perpendicularDirection of the vector product always perpendicular
to the plane containing the vectors andto the plane containing the vectors and .
A
C
BA
B
C
AB=C
BA=C
ABBA but AB=BA
B C
A
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
52/58
PHYSICS CHAPTER 1
52
The vector product of the unit vectors are shown below :
Example of vector product is a magnetic force on the straighta magnetic force on the straight
conductor carrying current places in magnetic fieldconductor carrying current places in magnetic field where the
expression is given by
x
z
y
k
j
i
jk=kj=iij=ji=k
ki=ik=j
ii=jj= k k=0ii=i2s in 0o=0jj=j 2s in 0o=0
k k=k2
s in 0o
=0
F=IlB F=IlB sin
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
53/58
PHYSICS CHAPTER 1
53
The vector product can also be expressed in determinant form as
11stst method :method :
22ndnd method :method :
Note :Note :
The angle between two vectorsThe angle between two vectorscan only be determined by using
the scalar (dot) productscalar (dot) product.
AB=i
j
kx y z
p q r
AB=yrzq ixrzp j xqyp k
AB=yrzq izpxr j xqyp k
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
54/58
PHYSICS CHAPTER 1
54
Given two vectors :
Determine
a) and its magnitude b)
c) the angle between vectors and .
Solution :Solution :
a)
The magnitude,
Example 1.12 :
AB=i
j
k3 2 1
1 0 5
AB AB
AB=2 5 1 0 i3 5 1 1 j3 0 2 1 kAB=100 i 151 j 02 k
A=3 i2 j k
B=i5 k
A B
AB=10 2 16 2 2 2
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
55/58
PHYSICS CHAPTER 1
55
Given two vectors :
Determine
a) and its magnitude b)
c) the angle between vectors and .
Solution :Solution :
a)
The magnitude,
Example 1.12 :
AB=i
j
k3 2 1
1 0 5
AB AB
AB=2 5 1 0 i3 5 1 1 j3 0 2 1 kAB=100 i 151 j 02 k
A=3 i2 j k
B=i5 k
A B
AB=10 2 16 2 2 2
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
56/58
PHYSICS CHAPTER 1
56
b)
c) The magnitude of vectors,
Using the scalar (dot) productscalar (dot) product formula,
AB= 3 i2 j ki0 j5 k
AB=2
AB= 3 1 ii2 0 jj1 5 kkAB=305
AB=AB cos
=cos1 ABAB =cos1 214 26
A=3 22 2 1 2=14
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
57/58
PHYSICS CHAPTER 1
57
1. If vector and vector , determine
a) , b) , c) .ANS. :ANS. :
2. Three vectors are given as follow :
Calculate
a) , b) , c) .
ANS. :ANS. :
3. If vector and vector ,
determine
a) the direction of
b) the angle between and .
ANS. : U think, 92.8ANS. : U think, 92.8
Exercise 1.4 :
2 k ; 26 ; 46
a=3 i5 j b=2 i4 jab ab abb
a=3i3
j2
k ; {
b=
i4
j2
k and { c =2
i2
j
k
abc abc abc 21;9 ;5 i11 { j9 k
P=3 i2 jk Q=2
i4
j3
kPQ
P Q
PHYSICS CHAPTER 1
-
7/28/2019 Physical quantities Matriculation STPM
58/58
PHYSICS CHAPTER 1
THE END
Next ChapterCHAPTER 2 :
Kinematics of Linear Motion
www.kms.matrik.e
du.my/physics
www.kms.matrik.e
du.my/physics