1. Concept of REST and MOTION 2. Motion and its different forms Translatory, Circulatory, Oscillatory, Vibratory, Periodic & Non-Periodic, Random, Uniform & Non-Uniform etc 3. Concept of MASS and WEIGHT. 4. Differentiate between MASS and WEIGHT.

1. WELCOME TO MY CLASS
Mr. Souvik Chatterjee
M.Sc (Physics)&B.Ed

2. MOTION
 Motion as a change in position of an object with time
 Types of motion
 Translatory
 Circulatory
 Oscillatory
 Repetitive (periodic and non periodic)
 Random
 Uniform and Non-uniform motion, Concept of distance and
speed(average speed)
 Weight
 Concept
 Differences between mass and weight

3. REST & MOTION
A body is said to be at rest if it does not
change its position with respect to a fixed
point in its surroundings.
A body is said to be in motion if it
changes its position with respect to a
fixed point in its surroundings.

4. EXAMPLE
A book lying on the table will not change its
position if it is not disturbed and will be
considered to be in a state of rest.
When a moving car changes its position with
respect to a tree or lamp post by the side of the
road, the car is said to be in motion

5. REST & MOTION ARE RELATIVE

7. EXPLANATION
Suppose we are sitting on a railway platform and
looking tree nearby, we say that the tree is at rest
because the tree does not change its position with
respect to us. But when we see a train passing out of the
station, we say that the train is in motion because it is
continuously changing its position with respect to us.
 For a passenger sitting inside a moving bus, the driver
of the bus, the driver of the bus is at rest because he
does not appear to change his position with respect to
the passenger . On the other hand the objects outside
the bus such as trees, buildings etc appear to be in
motion since they appear to change positions relative to
the passenger.

8. KEY POINTS
Every body in the universe is in motion. Everyday
we see bodies moving around us e.g birds flying,
cars and buses are moving, people walking,
insects crawling, animals running etc.
 Our earth also moves around the Sun. We often
say that a stone lying on the ground is at rest. But
indeed, the stone is also moving along with the
Earth around us.

9. An object can be in motion
relative to one set of
objects while at rest relative
to some other set of objects.
Thus rest and motion are
relative.

10. EXAMPLE
Suppose you are sitting in a room. You are at rest in
relation to all other stationary objects inside the
room. But the room (or home)is on earth and the
earth and the earth itself is not at rest. The earth
revolves around the sun. It takes one year to
complete one revolution around the sun. Thus,
you are also revolving with the earth around the
sun. Hence in relation to the sun you are in
motion

11. DIFFERENT TYPE OF MOTION
Different objects have different types of motion.
These different types of motion can be classified
into the following types.
1. Translatory Motion
2. Rotatory Motion
3. Circulatory Motion
4. Oscillatory Motion
5. Vibratory Motion
6. Periodic Motion, and
7. Non - periodic motion

12. TRANSLATORY MOTION
If an object like a vehicle, moves in a line such a way
that every point of the object moves through the same
distance in the same time, then then the motion of the
object is called translatory motion.

14. Translatory motion can be of two
types,
1. Rectilinear or linear motion &
2. Curvilinear motion

15. RECTILINEAR MOTION
If the motion of the body is along a straight
line, it is said to be a rectilinear motion.
e.g A ball falling from a height straight
towards the surface of earth, a car moving on a
straight road and a coin moving over a carrom
board etc.

17. CURVIINEAR MOTION
If the motion of a body is along a curved path,
it is said to be a curvilnear motion
e.g- Motion of a cyclist while taking a turn on
the road, car moving along a curved path and a
ball thrown by an athlete are in curvilinear
motion.

19. ROTATORY MOTION
A body is said to be in a rotatory motion if it moves
about a fixed axis.
A rotatory motion is different from a translatory motion
because in rotatory motion, the different part of the
object move through different distances during the
same time. The part of the body near the axis of
rotation travels a smaller distance than the distant parts
of the body.
e.g- The blades of a fan, a spinning wheel or a potter’s
wheel, a merry-go-round, rotation of the earth about its
own axis etc.

21. CIRCULAR MOTION
The motion of a body along a circular path is
called circular motion.
CIRCULAR motion is a special type of
curvilinear motion in which the distance of a
moving object from a fixed point (called
centre) does not change.
e.g- A girl is whirling a stone stone tied at the
end of a string in circular path, motion of earth
around sun,

23. DIFFERENCE BETWEEN CIRCULAR
MOTION & ROTATORY NOTION
In rotatory motion, the axis of rotation passes from a
point in the body itself whereas in circular motion, the
axis of revolution passes through a point outside the
body. Thus, the motion of earth around the sun is
circular whereas the motion of earth about its own axis
is rotational motion.
In circular and rotatory motion, the distance of a point of
the body from a fixed point always remains the same,
whereas it is not the same in curvilinear motion.

24. OSCILLATOTY MOTION
The to and fro motion of a body from its rest
position (or mean position) is called oscillatory
motion.
e.g- motion of a pendulum clock, motion of a
swing.

26. VIBRATORY MOTION
It is also an oscillatory motion with the difference
that in vibratory motion, a part of the body always
remains fixed and the rest part moves to and fro
about its mean position. During the vibratory
motion, the shape and size of the body changes.
e.g- When we breathe, one chest expands and
contracts, When the wire is plucked from the
middle, Musical instruments.

28. HOME WORK
 Define rest and motion. Give example.
 Explain ‘REST AND MOTION ARE RELATIVE’
 Define the following & Give three examples
 1.Translational Motion
 2. Rectilinear Motion
 3. Curvilinear Motion
 4. Rotatory Motion
 5. Circular Motion
 6. Oscillatoty Motion
 7. Vibratory Motion
 Differentiate between circular and rotatory motion.
 Differentiate between translatory and rotatory motion

29. PERIODIC MOTION
A motion which gets repeated after a regular interval of
time is called a periodic motion.
e.g- (i)The earth completes one revolution about the
sun in nearly 365 days and this motion is repeated after
365 days
(ii)The moon revolves around the earth and completes one
revolution in nearly 27.3 days and then repeats its
motion
(iii)A normal person’s heart beats every 0.8 second.
(iii)The pendulum of a wall clock repeats its motion after
every 2 s

31. NON-PERIODIC MOTION
The motion which does not repeat itself after a
regular interval of time is called non-periodic
motion
e.g-A footballer running on a field, application
of brakes in a moving vehicle, a ball rolling
down the ground gradually slows down and
finally stops and motion of tides in the sea.

33. ZIG-ZAG MOTION
The motion of particles (called molecules) of a liquid
or a gas is random or zig-zag or irregular because
they don’t take a specific path and specific direction
of motion.

34. MIXED MOTION
Sometimes a body can have more than one
type of motion simultaneously. Such a motion
is called a mixed motion
e.g- Wheel of a moving vehicles, A drill used
by a carpenter, A carpenter’s saw, A ball rolling
on the ground, Rotation of earth

35. WHEEL OF A MOVING VEHICLES
• Translational + Rotational

36. DRILLING MACHINE
• Rotatory + Translational Motion

37. CARPENTER’S SHAW
• Translatoty + Rotatory Motion

38. A BALL ROLLING ON THE GROUND
• Rotatory + Translational

39. ROTATTION OF EARTH
• Rotatory + Circular or Curvilinear

40. SPEED
Speed is defined by distance travelled by the
body in unit time
The S.I unit of speed is metre/second(m/s).
Other commonly used unit is
kilometre/hour(km/h)
18 km/h = 5 m/s

41. UNIFORM MOTION
If a moving body travels equal distances
in equal interval of time, its motion is
said to be uniform.
Thus for a uniform motion the speed of
the moving body remains constant.

42. EXAMPLE
Speed= 2m/s= (4-0)/2 m/s=(8-4)/2 m/s
=(12-8)/2 m/s=(16-12)/2 m/s

43. NON-UNIFORM MOTION
If a moving body travels unequal distances in
equal intervals of time, its motion is said to be
non-uniform
The speed is variable in different intervals of
time.

44. EXAMPLE
In the first interval=(5-0)/1=5m/s
In the second interval=(15-5)/1=10m/s
In the third interval=(30-15)/1=15m/s

45. AVERAGE SPEED
The average speed is calculated by finding the
ratio of the total distance travelled by the body
to the total time time taken in the journey.

46. HOME WORK
Define the following and write 3 examples of
each of them.
Periodic Motion
Non-periodic motion
Zigzag motion
Uniform Motion
Non-uniform Motion
Define Speed.
State its S.I unit.
Define Average Speed

47. • Define Mixed Motion. Give three
example and explain. In the example
you must mention the types of
motion that the body posseses.

48. NUMERICALS FROM CONCISE
PHYSICS
1.A car covers a distance of 160 km between two
cities in 4 h. What is the average speed of the car?
Average Speed = Distance/Time =160/4 = 40
km/h
2.A train travels a distance of 300 km with an
average speed of 60 km/h. How much time does it
take to cover the distance?
Time = Distance/Speed = 300/60 = 5 h

49. 3.A boy travels with an average speed of 10 m/s for 20
min. How much distance does he travel?
Time = 20 min = (20 X 60) =1200 s
 Distance = Speed X Time = (10 X 1200) m
= 12000 m = 12 km
4.A boy walks a distance of 30 m in 1 minute and
another 30 m in 1.5 minute. Describe the type of
motion of the body and find his average speed in m/s.
Non-uniform motion.
Total Distance = ( 30 + 30 ) = 60 m
Total Time = (1+1.5) = 2.5 minute = (2.5 X 60)s
= 150 s
Average Speed = 60/150 = 2/5 = 0.4 m/s

50. 5.A cyclist travels a distance of 1 km in the
first hour, 0.5 km in the second hour and 0.3
km in third hour. Find the average speed of the
cyclist in (i) km/h, (ii) m/s
Total Distance = (1 + 0.5 + 0.3)h = 1.8
km
Total Time = (1+1+1)= 3 h
(i)Average Speed = 1.8/3 = 0.6 km/h
 (ii) 0.6 km/h = (0.6 X 5)/18 m/s =
1/6 m/s= 0.167 m/s

51. 6. A car travels with speed 30 km/h for 30 minutes and
then with speed 40 km/h for one hour. Find:
(i)The total distance travelled by the car
(ii)The total time of travel, and
(iii)The average speed of car.
(i)First stage - time = 30 minute = 30/60 h = ½ h,
Distance = Speed X Time = (30 X ½) = 15 km
Second Stage – Distance = Speed X Time = 40 X 1 = 40
km
Total Distance = (40+15) = 55 km
(ii)Total time = (1+1/2) = 3/2 h =1.5 h
(iii)Average Speed = (55)/1.5 = 36.67 km/h

52. MASS
Mass of a body is the quantity of matter contained in it.
Mass of a body is constant and it does not change with
change in position of the body.
It is represented by a symbol M
S.I unit of mass is kilogram(kg).Smaller unit of mass is
gram(g).
1g= 1/1000 kg
The mass of a body is measured by a beam balance.
The mass of a body is expressed only by its magnitude( i.e
numbers and unit ) such as 10.0 kg. Here 10.0 is magnitude
and kg is unit.

53. WEIGHT
 The weight of a body is the force with which earth attracts the
body i.e weight of a body is the force of gravity on it.
 Weight of a body is not constant but it changes place to place.
 It represented by a symbol W.
 The S.I unit of weight is newton(N).
 One newton is nearly the force of attraction of earth on a mass
0.1 kg (or, 100 g).
 The other unit of weight is kilogram force(kgf) where 1 kgf =
10 N(More precisely 1kgf = 9.8 N)
 The weight of a body is measured by spring balance.
 Weight is expressed by stating its magnitude and direction.
 Its direction is always Vertically upwards.

54. The relationship between mass and weight is
 W= mg,
Where g=10 N/kg (nearly) (More precisely 9.8
N/kg)
Mass and weight are not the same
kg is the unit of mass whereas kgf is the unit
of weight. For example,a body of mass 10 kg
will have weight 10 kgf (or about
100 N)

55. EFFECT OF CHANGE OF PLACE
ON MASS & WEIGHT
The mass of a body remains constant every
where on the surface of earth or any other
heavenly body.
But the weight of the body changes from place
to place because it depends on the force of
attraction of earth (or other heavenly body) on
the body which differs from place to place

56. EXAMPLE
The mass of a body is same on earth’s surface
as well as on moon’s surface but the weight of
the body on moon’s surface is 1/6th of the
weight of the body on earth’s surface because
the force of attraction of moon on that body is
1/6th of the force of attraction exerted by the
earth.

57. DIFFERENCE BETWEEN MASS
&WEIGHT
(1) It is the quantity of matter contained in a body/ It
is the force with which the earth attracts the body.
(2)Its S.I unit is kilogram(kg)/ Its S.I unit is
newton(N)
(3)It is constant for a body and it does not change by
changing the place of the body/ It is not constant
for a body, but changes from place to place.
(4)It is measured by a beam balance/ It is measured
by a spring balance.

58. NUMERICALS FROM CONCISE
PHYSICS
7.On earth the weight of a body of mass 1.0 kg
is 10 N. What will be the weight of a body of
mass 37 kg in (a)kgf (b)N?
(a) Weight in N=(37 X 10)= 370 N
370 N=370/10=37 kgf
(b) 370 N

59. 8.The weight of a body of mass 6.0 kg on
moon is 10 N. If a body of mass 30 kg goes
from earth to the moon surface, what will be
his (a)mass,(b)weight?
(a) Mass is constant when the place is
changed. So mass remains same as 30 kg.
(b) Weight of 30 kg will be = (10 X 30)/6 =(10 X
5)= 50 N

60. HOME WORK
Define mass and weight
State their S.I unit of mass and weight
State the instrument by which mass and weight
are measured.
Define 1 kgf. How is it related to S.I unit of
mass?
Differentiate between mass and weight.
(Atleast 4 points)

61. SOME IMPORTANT QUESTIONS
 Name the type/types of motion performed by each of the following:
(a)Vehicle on a straight road
(b)Blades of electric fan in motion
(c)Pendulum of a wall clock
(d)Smoke particles from chimney
(e)Hands of a clock
(f)Earth around sun
(g)A spinning top
Ans.(a) Rectilinear/ Translatory/Rotatory
(b) Rotatory/Periodic
(c)Periodic/Oscillatory
(d)Random/Zigzag/Non-periodic
(e)Periodic/ Rotatory
(f) Translatory/Circular
(g) Rotatory/ Periodic

62. 2. State the types of motions of the following:
(a)A needle of a sewing machine
(b)The wheel of a bicycle
(c) The drill machine
(d) The carpenter’s saw
 Ans. (a) Periodic/Oscillatory
(b) Rectilinear/Translatory/ Curvilinear/Rotatory
(c)Translatory/Rotatory
(e)Translatory/Oscillatory

63. NUMERICAL
 A car travels 1/4 th of the total distance with speed 30 km/h, ½
th of the toatal distance with speed 40 km/h,last ¼ th of the
total distance with 10 km/h. Find the average speed.
 Ans. Let total Distance be d km
First Half , Distance= d/4 km, speed=30 km/h
Time= (d/4)/30 = d/120 h
Second half, Distance = d/2 km, speed 40 km/h
Time= (d/2)/40 = d/80 h
Third half, Distance = d/4 km, speed 20 km/h
Time = (d/4)/10 = d/40 h
Total time = (d/120 + d/80 + d/40)=d(1/120 +1/80+1/40)
=d/240(2+3+6)= 11d/240
Average Speed = Total Distance/Total Time = d/(11d/240) =
240/11 = 21.8 km/h.

64. HOME WORK
• If a train travels from A to B with a speed 20
km/h and returns from B to A with a speed 30
km/h. Find The average speed of the train?
• If a man walks 1/5 th of his journey with speed
15 km/h, next 3/5 th of his journey with speed
25 km/h and last 1/5 th of journey with a speed
5 km/h. Find the average speed of the man.

65. 1.Let the distance between two stations be d. km
From station A to B,
Distance travelled =d, Speed= 20km/h
Time=Distance/Speed=d/20 h
From B to A,
Distance travelled-d, Speed=30 km/h
Time=d/30 h
Average Speed= Total Distance/Total Time =
(d+d)/(d/20+d/30)=2d/d(1/20+1/30)
= (2 X 20 X 30)/(30+20)=1200/50 = 24 km/h

66. 2. Let the total distance be d km
First half, distance= d/5 km, speed= 15 km/h,
Time= Distance/ Time = (d/5)/15 = d/75 h
Second half, distance = 3d/5 km, Speed= 25 km/h
Time= (3d/5)/25 = 3d/125 h
Last half, Distance= d/5 km, Speed= 5 km/h,
Time = (d/5)/5=d/25 h
Total Time = (d/75 + 3d/125 + d/25) = d(1/75 + 3/125
+ 1/25) = d/375(5 + 9 +15) = 29d/375 h
Average Speed = Total distance / Total Time =
d/(23d/375) = 375/29 = 12.93 km/h

67. THANK YOU