Kinematics, Prepared By Engr. Ali Dawoodi

Physics IX, Chapter 2,Prepared by Engr. Ali Asghar
ali.dawoodi52@gmail.com
1

Aga Khan Board
Physics IX
Chapter 2
Kinematics
2

Must Remember….
Note
Solve all quick quiz, mini exercise, numerical example and problem
question from Punjab and Sindh book.
This handout will serve as helping hand for you but you have to read
books and prepared your own notes from books to do best in board
exam
3

SLO 2.1.1 (U): Describe using example that how object can be at rest
and in motion simultaneously.
4

Rest and Motion at same time
Rest: A body is said to be in rest, if it
does not change its position with
respect to its surrounding
e.g: Passengers are sitting
Motion: A body is said to be in motion,
if it changes its position with respect to
its surrounding.
e.g: Aero plane is travelling
5

SLO 2.2.1 (U): Describe different types of motion i.e. translator, rotatory
and vibratory motion and distinguished among them.
PB Pg. 29 to PB Pg.32
6

Types of motion
Motion
Translatory motion
Linear, random and circular
Rotatory motion
Vibratory motion
To and fro motion
7

Translatory Motion
Linear Motion
Straight line motion of a body is called
linear motion
Circular Motion
The motion of a body in a circular path
is called circular motion
8

Translatory Motion
Random Motion
The disorder or irregular motion
of an object is called random
motion
9

Rotatory Motion
Spin Motion
The spinning motion of a body
about its axis is called its rotatory
motion
10

Think.. What is difference between spin and
circulatory motion
Note:
In circulatory motion, the point
about which a body goes around,
is outside the body. In rotatory
motion, the line around which a
body moves about, is passing
through the body itself
11

Vibrating Motion
To and Fro Motion
To and fro motion of a body about
its mean position is known as
vibratory motion
E.g. pendulum of a clock
12

SLO 2.3.1 : Define the term speed, velocity and acceleration and write
their formulae
PB pg 35
13

Speed
Definition:
Distance cover by a object in unit of time is
called speed.
Formula
Speed = Distance / time
Distance = speed x time
Unit = m/s
Uniform Speed
A body cover equal distance in equal interval of
time.
14

Velocity
Definition:
Displacement (shortest distance between two
point) cover by a object in unit of time is called
velocity.
Formula:
Velocity = Displacement / time
V= d/t unit m/s
Uniform Velocity
A body cover equal displacement in equal
interval of time.
15

Acceleration
Acceleration
The rate of change of velocity of a
body
acceleration = change in velocity / change in time
acceleration = final velocity – initial velocity / change in time
a = Vf - Vi / t2 – t1 unit m2 / sec
Uniform Velocity
A body cover equal change in velocity in equal
interval of time
16

SLO 2.3.2: Differentiate between distance and displacement; speed and
velocity.
17

Term Associate with Motion
Distance
The length of a path between two
points is called distance
Displacement
The shortest distance between the two
point with magnitude and direction
18

Term Associate with Motion
Speed
The distance cover by an object in unit time
is called speed.
Speed = Distance / time
Distance = speed x time
S = Vt unit m/s
Uniform Speed
A body cover equal distance in equal
interval of time.
Velocity
The rate of change of displacement(shortest
distance) is called velocity.
Velocity = Displacement / time
V= d/t unit m/s
Uniform Velocity
A body cover equal displacement in equal
interval of time.
19

SLO 2.4.1 (K): Define scalars and vectors quantities
PB Pg. 33.
20

Scalar and Vector
Scalar
The quantity is describe completely by
its magnitude only
Vector
The quantity is describe completely by
its magnitude and direction
21

Representation of a vector
Vector is represent by the bold
letter A,B etc or a bar or arrow
over their symbol A , B , A, B
Graphically vector represent by a
line segment with arrow ahead.
22

SLO 2.4.2 (U): Differentiate between scalars and vectors quantities
PB Pg. 35
23

Scalars and Vectors Quantities
Scalar
Distance
The length of a path between two
points is called distance
Speed
The distance cover by an object in
unit time is called speed.
Vector
Displacement
The shortest distance between the two
point with magnitude and direction
Velocity
The rate of change of
displacement(shortest distance) is
called velocity.
Acceleration
The rate of change of velocity of a body
24

SLO 2.5.1 (K): Define like and unlike parallel forces
PB Pg. 86
Internet
25

26

SLO 2.6.1 (U): Describe head to tail rule of vectors addition of forces l
vectors;
SLO 2.8.1 (A): Draw the vector quantity using graph
SB Pg. 73 to SB Pg. 75
PB Pg. 87 to PB Pg. 88
27

Head to tail rule
We can add the vectors with the
head to tail rule, the head of first
vector join with the tail of second
vectors, similarly for next vector.
Resultant vector joint the tail of
first vector and head of last vector
Do e.g. from book
28

SLO 2.7.1 (U): Describe resolution of forces into its perpendicular
component.
SLO 2.7.2 (A): Determine magnitude and direction of a force from its
perpendicular component.
PB Pg. 88-90
SB Pg. 77-79
29

Resolution of forces
Resolution of force
Splitting up the force into its two
mutually perpendicular
components is called the
resolution of that force.
F = Fx + Fy
See book.
30

Determine the force
Determine the force
Since the force is resolve into its
two perpendicular component. Its
reverse is to determine the force
knowing its perpendicular
component.
See book
31

SLO 2.8.2 (A): Plot and interpret distance-time graph and speed-time
graph
SLO 2.8.3 (A): determine and interpret the slope of distance-time and
speed-time graph
SLO 2.8.4 (A): determine from the shape of the graph, the state of a
body (i) at rest, (ii) moving with constant speed and (iii) moving with
variable speed
SLO 2.8.5 (A): calculate the area under speed-time graph of uniformly
accelerated objects to determine the distance
PB; Pg. 40 to 44
32

SLO 2.9.1 (U): derive equations of motion for a body moving with a
uniform acceleration in a straight line
SB; Pg. 38 to 40
33

Derivation: S = Vt
The average velocity “V” is defined as the displacement “S” travelled
during a particular time interval “t” divided by the time interval.
Ave. Velocity = Displacement Travelled = S
Time Interval t
V = S
t
S = Vt
34

First Equation of Motion
Consider a body with initial
velocity ‘Vi’ which changes to final
velocity ‘Vf’, in a small time
interval ‘t’.
So, the change of velocity
= Vf - Vi
the change of velocity in unit time
= Vf - Vi
t
•
35

First Equation of motion
Consider a body with initial velocity ‘Vi’ which changes to final velocity
‘Vf’, in a small time interval ‘t’.
So, the change of velocity = Vf - Vi
the change of velocity in unit time = Vf - Vi
t
This change of velocity per unit time is the acceleration of the body
denoted by ‘a’, thus a = Vf - Vi
t
or Vf - Vi = at
or Vf = Vi + at
36

Second equation of motion
‘Vf’, in a small time interval ‘t’. Its acceleration is ‘a’ and the
displacement covered by the body in this time interval is ‘S’.
The average velocity of this body is given as
Average Velocity = Vi + Vf
2
or Average Velocity = S
t
37

Second equation of motion
Thus S = Vi + Vf or S = Vi + Vf x t
t 2 2
Now, as per the first equation of motion, Vf = Vi + at,
Thus S = Vi + Vi + at x t
2
S = 2Vi + at x t
2 S = (2Vi + at) x t
2 2
S = Vit + 1at2
2
38

Third equation of motion
‘Vf’, in a small time interval ‘t’. Its acceleration is ‘a’ and the
displacement covered by the body in this time interval is ‘S’.
The third equation of motion can be obtained by using the first and
the second equation of motion.
As per the first equation of motion,
Vf = Vi + at
Squaring both sides, we get
(Vf)2 = ( Vi + at )2
39

Third equation of motion
Vf
2 = (Vi)2 + 2(Vi)(at) + (at)2
Vf
2 = Vi
2 + 2Viat + a2t2
Vf
2 = Vi
2 + 2a(Vit + 1at2)
2
As per the second equation of motion, Vit + 1at2 = S,
2
Thus, Vf
2 = Vi
2 + 2aS
40

Motion of freely falling body
Galileo said that freely falling
body have same acceleration
independent of their masses.
This is due to gravitational
constant (g), its value is
approximately 10m/s2
g is positive when body fall down
and negative when body move up
41

SLO 2.9.2 (A), 2.10.1 (A):
• solve problems related to uniformly accelerated motion using
appropriate equations
• solve problems related to freely falling bodies using 10ms-2 as the
acceleration due to gravity
• Solve: PB Example: 2.2 to 2.5, 2.11 to 2.15 (Pg. 37 to 50) & Problem
2.1 to 2.10 (Pg. 54)
• Solve: SB All example (Pg. 36 to 43) & Problem 3.1 to 3.13 (Pg. 44, 45)
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Kinematics, Prepared By Engr. Ali Dawoodi

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