This is a ppt on motion for class 9 studying students, hope you like it. If you have any questions message me on http;//sh.st/PVqfi Regards Mridul Verma Innocent Hearts School

1. Life is a full circle, widening until it joins the circle
motions of the infinite

2. What is Motion
Motion :- It is the change in position of a body with time. Motion can be
described in terms of the distance moved or the displacement.
Concept :- In physics, motion is a change in position of an object with
respect to time. Motion is typically described in terms
of displacement, distance, velocity, acceleration, time and speed. Motion
of a body is observed by attaching a frame of reference to an observer
and measuring the change in position of the body relative to that frame.
Mridul Verma | 9 "A" | 10 2

3. Mridul Verma | 9 "A" | 10 3

4. DISTANCE
Distance moved :- It is the actual length of the path travelled by a body.
Mridul Verma | 9 "A" | 10 4
Total Distance
covered in ONE
LAP = 400m
Starting & Ending
point

5. DISPLACEMENT
Displacement :- It is the length of the shortest path travelled by a body
from its initial position to its final position.
Mridul Verma | 9 "A" | 10
5
Total
displacement in
ONE LAP = 0
Starting & ending
point

6. SPEED
Speed :- Speed of a body is the distance travelled by the body in unit
time.
Speed = Distance
Time
If a body travels a distance s in time t then its speed v is
v = s
t
The SI unit of speed is metre per second m/s or ms -1
Since speed has only magnitude it is a scalar quantity.
Mridul Verma | 9 "A" | 10 6

7. VELOCITY
The rate of motion of a body is more meaningful if we specify its direction of
motion along with speed. The quantity which specifies both the direction of
motion and speed is velocity.
Velocity :- Velocity of a body is the displacement of the body per unit time.
Velocity = Displacement
Time taken
Since velocity has both magnitude and direction, it is a vector quantity.
Mridul Verma | 9 "A" | 10 7

8. ACCELERATION
The quantity which specifies changes in velocity is acceleration.
Acceleration :- It is the change in velocity of a body per unit time. ( or
the rate of change of velocity.)
Acceleration = Change in velocity
Time
If the velocity of a body changes from initial value u to final value v in
time t, then acceleration a is
a = v - u
t .The SI unit of acceleration is ms - 2
Mridul Verma | 9 "A" | 10 8

9. PLOTTING POINTS
Mridul Verma | 9 "A" | 10 9
We already know how to plot points on a graph. So let`s recall them. Suppose I
want to plot points (3, 4) on a graph, it will be as follows :-
0
1
2 3 4 51
2
3
4
5
Y
X
Points to plot (3, 4)
X = 3
Y = 4
In this similar way, we can plot many other
points on a graph.

10. GRAPHS AND ITS
TYPES• A graph is a pictorial representation of observation. It consist of two
variables, one is independent variable and other is dependent variable.
• Independent variable is taken along X-axis and dependent variable is taken
along Y-axis.
• There are many types of graphs in physics, some of them are as follows :-
1. Distance time graph 2. Displacement time graph
3. Velocity time graph 4. Acceleration time graph
Mridul Verma | 9 "A" | 10 10

11. DISTANCE TIME
GRAPHThe change in the position of a body with time can be represented on
the distance time graph. In this graph distance is taken on the Y – axis
and time is taken on the X – axis. The distance time graph for uniform
speed is a straight line ( linear ).
This is because in uniform speed a body travels equal distances in equal
intervals of time. We can determine the speed of the body from the
distance – time graph.
They are used to find speed or velocity of body.
The slope of it gives speed of body.
Mridul Verma | 9 "A" | 10 11

12. Mridul Verma | 9 "A" | 10 12
There are 3–Types of distance time
graphs.1. When body is at rest – It`s a straight line parallel to time axis.
t
d
2. When body is mpving with uniform speed – when the body is moving with uniform speed
the graph is a straight line making an angle with the time axis and the slope of this graph
is given by - slope = Y2 – Y1 / X2 – X1 which is equal to speed.
t
d

13. Mridul Verma | 9 "A" | 10 13
3. When a body is moving with Non uniform speed – The body covers unequal
distances in equal intervals of time.
t
d
t
ddecreasing
speed
increasing
speed
These curves are called parabola.
So, greater the angle, greater is the slope and greater is the speed

14. DISPLACEMENT TIME
GRAPH
Mridul Verma | 9 "A" | 10 14
It is a vector quantity and it`s slope gives velocity.
There are 3-Types of displacement time graph, they are as follows :-
1. When body is at rest -
t
s Slope of this graph is 0.

15. Mridul Verma | 9 "A" | 10 15
2. Body moving with uniform speed -
t
s Q1
Q2
A
B Where Q1 > Q2
Velocity of A > Velocity of B
3. Body moving with variable/non uniform velocity -
t
s velocity
increases s
velocity
decreases
t

16. VELOCITY TIME
GRAPH
Mridul Verma | 9 "A" | 10 16
For a body moving in straight line, without changing it`s direction, velocity of
body becomes equal to it`s speed.
The slope of velocity time graph gives acceleration of body.
The area under this graph gives the value of distance travelled.
There are 3 different cases of this graph, which we have discussed next -

17. Mridul Verma | 9 "A" | 10 17
CASE - I
If the body is moving with constant speed.
t
v Slope = 0
Acceleration = ms - 2
Constant speed – If the body moves with constant velocity/speed then graph is straight
line parallel to time axis and slpoe and acceleration will be 0.

18. Mridul Verma | 9 "A" | 10 18
CASE - II
When a body is moving with uniformly changing speed -
a.) If speed increases uniformly.
v
t
This slope is known as positive slope and slope gives
uniform acceleration.
b.) If speed is decreasing uniformly -
v
t
The graph is straight line slope downwards. Hence, the slope is
negative. The slope of this graph gives retardation.
Area in both cases (a & b) gives distance travelled by body.

19. Mridul Verma | 9 "A" | 10 19
CASE - III
Non uniformly changing speed.
a.) If speed increases non uniformly.
v
t
The graph is a curve moving upward. The slope of tangent
drawn at any point on curve is positive and is equal to
acceleration of body.
b.) If speed decreases non uniformly.
t
v The graph is a curve moving downwards and the slope of
tangent is negative and gives the value of retardation.

20. ACCELERATION TIME
GRAPH
Mridul Verma | 9 "A" | 10 20
The graph is as shown below -
CASE - I
V
t
For a body at rest -
Acceleration is 0 for a body at
rest or when is moves with
uniform speed
CASE - II
For a body moving with uniform acceleration.
slope = 0
t
a
-a
slope = 0
In uniform acceleration the acceleration is constant and
does not change and hence the graph is straight line
parallel to time axis.

21. EQUATIONS OF MOTION BY
GRAPHICAL METHOD
Mridul Verma | 9 "A" | 10 21
The motion of a body moving with uniform acceleration can be described
with the help of three equations called equations of motion.
The equations of motion are :-
i) v = u + at
ii) s = ut + ½ at2
iii) 2as = v2 – u2
Where u - is the initial velocity
v - is the final velocity
a - is acceleration
t - is the time
s - is the distance traveled

22. CIRCULAR
MOTION
Mridul Verma | 9 "A" | 10 22
The motion of a body in a circular path is called circular motion.
Uniform circular motion :- If a body moves in a circular path with uniform
speed, its motion is called uniform circular motion.
Uniform circular motion is accelerated motion because in a circular motion a body
continuously changes its direction.
The circumference of a circle of radius r is given by 2πr. If a body takes time t to go once
around the circular path, then the velocity v is given by
v = 2πr
t

23. Mridul Verma | 9 "A" | 10 23
Thanks for watchin
Name – Mridul Verma
Class – 9 – A
Roll No. - 10©Mridul Verma