2. Contents Introduction
Motion
Rest
position
Reference point
Distance
Displacement
Types of motion
Rate of motion
◦ Speed
◦ Velocity
◦ Acceleration
◦ Graphical representation
◦Three motion equations
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3. Introduction
Everything in the galaxy moves.
But based on the reference person it may be
under movement or at rest
Movement motion
Motion
◦ An object is in motion, when its position changes
with time.
Direct evidence of motion moving bus, two
wheelers, fish, birds, earth, moon, video , tree
branches etc
Indirect evidence identification of air
movement by observing the movement of
dust, branches of tree and leaves etc
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4. Rest
A body is said to be at rest if it does
not change its position with respect to
the surroundings and time.
For example a book on the table, a
house, a tree etc,.
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5. RELATION B/W REST AND MOTION
An object may be moving for one
person and stationary for another
person.
Eg, Passengers on moving bus and
peoples who stands out.
Rest and motion are relative. For
example a man standing still on the
earth is at rest with respect to the
earth. But he is in motion with respect
to the Sun.
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6. REFERENCE POINT
The particular point about which the
position of the object is defined, is
called reference point or origin.
It is the point from which the location
of object is measured. It is called as
origin. Any object can be located only
with the help of reference point and its
direction.
Eg. The school in a village is 6 km
south from my home
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7. Have you ever experienced that the
train in which you are sitting appears
to move while it is at rest?
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8. We sometimes are endangered by the
motion of objects around us, especially
if that motion is erratic and
uncontrolled as observed in a flooded
river, a hurricane or a tsunami.
On the other hand, controlled motion can be
a
service to human beings such as in the
generation of hydro-electric power.
Do you feel the necessity to study the
erratic motion of some objects and
learn to control them?
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9. Note
Scalar quantities: physical
quantities associate only with
magnitude i.e. numbers. Eg, mass,
time, distance, speed etc.
Vector quantities: :physical
quantities associate with magnitude
i.e. numbers as well as direction. Eg.
Weight, displacement, velocity etc.
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10. Types of motion
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•Circulatory motion/circular motion – in a circular path
•Linear motion – in a straight line path
•Oscillatory/vibration motion – to and fro path with respect to
origin
11. Distance
The length of the actual path covered
by a body in a given time is called
distance.
It is a scalar quantity.
C.G.S → centimeter (cm)
S.I.→ metre(m)
Always positive
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12. Displacement
The shortest distance between the
initial and the final positions of the
body along with the direction of motion
is called displacement.
It is a vector quantity.
Units: C.G.S → centimeter (cm)
S.I.→ metre(m)
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13. Distance vs Displacement
Displacement of a moving object can
never be greater than the distance
travelled by it.
Displacement < = distance
Displacement / Distance <=1
If a body moves along a straight line, then
distance and displacement will be equal
Displacement can be + - or 0 but distance
is always +
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15. Sl. No. Differentiating
Property
Distance Displacement
1 Definition The complete length of the
path between any two
points is called distance.
Displacement is
the direct shortest
length between
any two points
when measured
along the
minimum path
between them.
2 Denotation s d
3 Direction
Consideration
To calculate distance,
direction is not considered.
To calculate
displacement,
direction is taken
into consideration.
4 Quantity Distance is a scalar quantity
as it only depends upon the
magnitude and not the
direction.
Displacement is a
vector quantity as
it depends upon
both magnitude
and direction.
17. Similarities between distance
and displacement:
Both distance and displacement have
same unit of measurement , in S.I.
unit it is meter.
Both distance and displacement have
magnitude. If the body travels on a
straight line unidirectionally, both
becomes equal in magnitude.
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18. Activity ______________ 8.3
Take a metre scale and a long rope.
Walk from one corner of a basket-ball
court to its oppposite corner along its
sides.
Measure the distance covered by you
and magnitude of the displacement.
What difference would you notice
between the two in this case?
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19. Activity ______________ 8.4
Automobiles are fitted with a device
that shows the distance travelled.
Such a device is known as an odometer.
A car is driven from Bhubaneshwar to
New Delhi. The difference between the
final reading and the initial reading of
the odometer is 1850 km.
Find the magnitude of the displacement
between Bhubaneshwar and New Delhi
by using the Road Map of India.
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20. Uniform and non uniform
motion:
Uniform Motion Non-Uniform Motion
It is a motion in which equal
distance is covered in equal
time intervals of time intervals.
It is a motion in which unequal
distance is covered in equal
intervals of time.
Distance travelled by an object
in uniform motion increases
linearly.
Non linear.
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22. Measuring the rate of motion :
(Speed)
What is km/hr?
Km/hr = 1000/3600 m/sec
= 10/36 m/sec
1 km/hr = 5 / 18 m /sec
1 km / hr = 1000/60 m/min
1 km / hr = 1/60 km / min
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23. 1. Speed:
The distance travelled by the body per
unit time is called speed. It is a scalar
quantity. Speed can either be positive
or zero. But never negative
Units: C.G.S → cm s⁻1 , S.I. →m s -1
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24. Average speed:
The ratio of total distance travelled to
total time taken by the body gives
average speed.
Total distance
Average speed =
Total time taken
S.I. unit of speed →m s -1
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25. Instantaneous speed:
It is a measure of distance covered at
every instant of time
The speed of an object at any
particular instant of time or at a
particular point of its path is called the
instantaneous speed of the object.
Speedometer is a device which is
used to measure instantaneous speed
of a moving body.
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26. Uniform Speed:
Moving body covers equal distance in
equal interval of time. i.e. constant
speed
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27. Non – uniform Speed:
Moving body covers unequal distance
in equal interval of time. i.e. variable
speed.
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29. H/W
An object travels 10 km in 2 sec and
4 km in 10 mins. What is the average
speed of an object?
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30. 2.[ Speed with Direction ]:
Velocity:-
The ratio between the displacement of the body
per unit time is called velocity.
Velocity can be either positive or zero or
negative.
Velocity is a vector quantity.
Speed of an object moving in a definite
direction within certain time period is known
as velocity.
Displacement (d)
Velocity(v)=
Time (t)
Units: C.G.S → cm s⁻1 , S.I. →m s -1
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31. Uniform velocity:
If an object covers equal
displacements in equal intervals of
time , then its velocity is known as
uniform velocity. i.e. constant velocity.
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32. Non-Uniform velocity:
If an object covers unequal
displacements in equal intervals of
time, then its velocity is known as non-
uniform velocity. i.e. variable velocity.
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33. Average velocity:
The ratio of total displacement
travelled to total time taken by the
body gives its average velocity.
Total
displacement
Average velocity =
Total time taken
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•Average speed is always greater than average velocity.
•If body returns to its initial position, average velocity will be zero
but average speed will not be zero.
•When direction of motion changes, velocity also changes.
35. Instantaneous velocity:
It is the velocity of an object in motion
at a specific point of time.
Speed and velocity are not always
equal in magnitude.
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40. 3.Rate of Change of Velocity:
Acceleration
The rate of change of velocity of a
body per unit time is called
acceleration
Acceleration(a) =
Unit : C.G.S → cm s-2, S.I. → m s-2
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41. So change in velocity will never
be zero
If a body moves with uniform or
constant velocity, then the
acceleration is equal to zero.
If velocity increases, acceleration
increases
If velocity decreases, acceleration
decreases. In this acceleration will
be negative.
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42. The acceleration is taken to be
positive if it is in the direction of
velocity and negative when it is
opposite to the direction of the
velocity.
Negative acceleration is also known
as deceleration or retardation.
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43. Uniform acceleration:
When velocity of body changes by
equal amounts in equal time intervals,
acceleration is said to be uniform.
E.g. the motion of a freely falling body.
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44. Non- Uniform acceleration:
When velocity of body changes by
unequal amounts in equal time
intervals, acceleration is said to be
non-uniform.
E.g. the movement of a car in a
crowded city road.
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50. Graphical representation
a. Distance – Time Graph
(speed)
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* A change in position of an object with respect to time.
X axis Time
Y axis Distance
Applicable for an object moves at uniform, non uniform or at rest pos
[Uniform Speed]
52. b. Velocity – Time Graph
(acceleration)
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•The variation in velocity with time of an object
•X axis Time
•Y axis Velocity
53. Area under velocity time graph gives
distance
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Uniform motion – constant velocity (zero acceleration)
54. Area under velocity time graph gives distance
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#From Velocity Time Graph both acceleration and distance can be
Uniform motion – change in velocity with uniform acceleration
