NCERT

1. St. Vincent Pallotti School, Besa
Class VI
Science
LESSON 10
MOTION AND
MEASUREMENT OF
DISTANCE
Part : I
By : Suvarna Wadbudhe

2. In Part I, you will learn about :
 Motion
 Types of Motion
 The story of Transport

3. Motion: An object is said to be in motion ( or moving ) when it
changes with time.
For example. When the car changes its position with time we say
that the car is moving or that the car is in motion.
A moving car
A
After five seconds car
reaches here
B

4. Types of
Motion
Rectilinear
Motion
Periodic
Motion
Rotational
Motion
Circular
Motion

5. Rectilinear Motion : Motion in a straight line is called rectilinear motion.
Motion of cyclist
March-past of soldiers
Motion of vehicle
Motion of sprinter ( short
distance runner )
Example

6. Motion of a girl sliding
down a slope
Motion of stone falling
A ball rolling on the
ground
Motion of striker on
the carrom board

7. Circular Motion: When an object moves along the circular path, it is circular motion.
Example
Movement of moon
around the earth
Movement of earth around the
sun
Movement of artificial
satellite around the earth

8. We can demonstrate circular motion by a simple activity
as follows:
• Take a piece of stone, tie it to a thread and whirl it
(move it round and round rapidly) with your hand by
holding the other end of thread.
• We will see that the stone moves along a circular path.
• Thus, a stone tied to a thread and moved round and
round rapidly undergoes circular motion.
• When the stone tied to a thread is moving round and
round, then the distance of stone from our hand
remain the same all the time.
• Thus, in circular motion, the object moves in such a
way that its distance from a fixed point (say, the
centre of circular path) remains the same.
Activity

9. Movement of tip of the
hand of a clock
movement of blades of fan
movement of child sitting
on merry-go round

10. Periodic Motion: The motion that repeat itself after regular interval of time, is called
periodic motion.
Example
Movement of moon
around the earth
Movement of earth around the
sun
Movement of artificial
satellite around the earth

11. Movement of seconds’
hand, minutes’ hand
and hours’ hand of a
clock
Motion of branch of a tree
movement of swing

12. Swinging of pendulum
Vibration of string of
guitar or sitar
Vibration of skin of
tabla or dholak

13. Rotational Motion: When an object turns ( or spins ) about a fixed axis, it is called
rotational motion.
Example
Spinning of earth on its axis
Motion of spinning of
top
Rotation of windmill

14. Turning of bicycle’s wheel
Turning of potter’s wheel
Turning of merry-go round

15. Objects having more than one type of Motion

16.  The earth moves around the sun,
so it is circular motion.
 The earth repeats its motion
around the sun after regular
interval of time ( of one year ),
so it has periodic motion.
 The earth rotates on its axis, so
it shows rotational motion.
Thus, the earth has three types of motion at the same time -
circular motion, periodic motion and rotational motion.
1. The Case of Earth

17.  The outer part of merry-go-round ( on
which children sit ) shows circular
motion.
 It we consider merry-go-round as a
whole, then it shows rotational motion,
because it turns on an axle.
Thus, a merry-go-round has two types of motion at the same
time - circular motion and rotational motion.
2. The Case of Merry-Go-Round

18.  A bicycle moving on a straight road
shows rectilinear motion.
 A wheel of bicycle rotates on its axle
showing rotational motion.
Thus, a bicycle has two types of motion at the same time -
rectilinear motion and rotational motion.
3. The Case of Bicycle

19.  A ball moving forward on a straight road
shows rectilinear motion.
 A ball rotating while moving forward
shows rotational motion.
Thus, a ball has two types of motion at the same time -
rectilinear motion and rotational motion.
4. The Case of Ball

20.  A wheel of sewing machine rotates on its
axle, showing rotational motion.
 A needle of sewing moves up and down
continuously ( as long as the wheel rotates )
shows periodic motion.
Thus, a sewing motion has two types of motion at the same
time - periodic motion and rotational motion.
5. The Case of a Sewing Machine

21. The Story of Transport
1. People used to move on foot or on
animals.
2. They used to carry loads
on animals.
3. Then they used boats for
transport along water
routes such as river.

22. The invention of wheel made a great change in the modes of transport.
4. The wheels were
used in making the
transport vehicles
such as bullock-
carts, horse-carts and
camel-cart

23. 5. The invention of wheel
led to the development of
bicycle.
6. The discovery of steam engine in the
beginning of 19th century brought a
second revolution in the field of
transport. Animal power could now be
replaced by engine power.

24. The invention of petrol and diesel engine in the second half of 19th century, gave us vehicles
called automobiles ( such as cars, buses, trucks, motorcycles and scooters) for travel on land.

25. Motorised boats and ships were developed as a means of transport on water
( such as rivers and sea ).

26. Aeroplanes and helicopters were developed as a means of transport in the
early 20th century.

27. Electric trains,
monorails,
supersonic
aeroplanes and
spacecrafts are also
some of the 20th
century
contributions to the
modes of transport.