9 – Motion and Types of
Motion
Q. 1. Fill in the blanks:
Linear,
non-linear, circular, uniform linear, non-uniform linear, uniform circular, non-uniform
circular, random)
(1) If
a ball is released from a terrace of a building, it comes down in .........
motion.
On the
other hand, it reaches the ground in motion, if it is thrown with
force
away from the terrace in a direction parallel to the terrace.
(2)
The motion of an aeroplane on the runway before take-off is...............
(3)
The kite looking for its prey flies with ............ motion in the sky.
(4)
Children sitting in a rotating giant wheel have ... ..... motion, while those
sitting in
a
merry-go-round have a .............. motion.
Ans.
(1) If a ball is released from a terrace of a building, it comes down in
non-uniform
linear
motion. On the other hand, it reaches the ground in non-linear motion, if
it is
thrown with force away from the terrace in a direction parallel to the terrace.
(2)
The motion of an aeroplane on the runway before take-off is linear.
(3)
The kite looking for its prey flies with circular motion in the sky.
(4)
Children sitting in a rotating giant wheel have uniform circular motion, while
those
sitting
in a merry-go-round have a non-uniform circular motion.
Q. 2. Identify the types of motion : Ans.
(1)
Movement of the earth around the sun. Circular, periodic
(2)
Movement of a ceiling fan. Oscillatory,
circular
(3) A
meteor falling from the sky. Linear
(4) A
rocket launched from the ground. Linear
(5) A
fish swimming in water. Random
(6)
The plucked string of a sitar. Oscillatory
Q. 3. How are we different?
(1)
Oscillatory motion and linear motion :
Ans. Oscillatory motion
Linear motion
(1)
Oscillatory motion is a type of non- (1) Objects showing linear
linear
motion. The objects in this type move in a straight line.
of
motion never move in a straight line.
(2)
The object showing oscillatory motion (2) The object showing
linear
comes
back to its original place again motion is displaced
away from
and
again. the original place.
(3) e.g the table fan and ceiling fan. (3) eg. Running vehicles, parade merry-go-round
and giant wheel. the Or soldiers.
pendulum
of a clock.
(2) Linear motion and random motion :
Ans. Linear motion
Random motion
In linear motion, the object travels in a (1) In random motion, the object straight
line and in the same direction travels in any
direction an with
Continuously changing speed
(2)
Objects displaying linear motion (2)
Objects displaying random
always
travel in a straight line.
Motion never
travel in one
straight line.
(3)
e.g. Moving train, parading soldiers (3)
e.g. Flying birds. swimming
fish
(3) Random motion and oscillatory
motion :
Ans. Random motion
Oscillatory motion
(1) The motion that changes its direction (1) The motion in which an object
and
speed continuously is called goes in one
direction and comes
random
motion
back again to the original position is
called oscillatory motion.
(2)
The random motion is a non-linear (2) Oscillatory motion is
non-linear
motion
and does not have a fixed motion and has a
fixed direction.
direction
(3)
The objects showing random motion. (3) The
objects showing oscillatory
motion
may not come back to the original motion come back to the
original
position.
position.
(4) e.g. Flying butterflies and bird, game (4) e.g. Pendulum of a clock. needle
of
football
sewing
machine, table fan and ceiling fan.
Q 4.
Explain in your own words, giving one example each :
(1) Linear
motion.
Ans.
The motion of an object travelling in a straight line or in the same direction
is called linear motion. There are two types of linear motion, viz. uniform
linear motion and non-uniform linear motion. the distance traversed by an
object along a straight line in unit time is the same. Whereas, in non- uniform
linear motion. The distance traversed by an object along a straight line in
unit time keeps on changing e.g. the parading
soldiers show uniform linear motion, whereas the children playing on a slide
show non-uniform linear motion
(2) Oscillatory motion.
Ans. The
motion of a body that is moving in back and forth direction is called
oscillatory motion. Oscillations form oscillatory motion. Oscillatory motion is
a type of non-linear motion. If the oscillatory motion is completed in fixed period
of time, it becomes a periodic motion. e.g the swinging pendulum of a clock,
the needle of a sewing machine
And
vibrating diaphragm of different musical instruments.
(3) Circular motion.
Ans. The motion of an object along a circular path is called circular motion.
Circular motion can be periodic motion
if it is taking place in fixed time period. In day-to-day life many objects are seen completing circular
path. The hands of the clock show circular and periodic motion. The giant
wheel, merry-go-round, mixer, fans, etc. show circular motion.
(4) Random motion.
Ans. The motion that changes its speed and
direction continuously is called random on There is no fixed direction for
random motion. The butterflies, birds flying in the the wandering animals, the
swimming fish, etc. show random motion.
(5) Periodic motion.
Ans.
The motion in which moving object passes through a certain point again and
again after a fixed period is called periodic motion. The hands of the clock
complete their rotations in fixed time period. A merry-go-round also completes
the rounds in specific time. Therefore this kind of motion is called periodic
motion.
Q. 5. Answer the following questions
in your own words:
(1)
Which types of motion are seen in birds flying in the sky ?
Ans.
The birds flying in the sky show oscillatory motion when they flap their wings.
Most of the birds show linear motion. Some like kite display circular motion.
Crows are seen moving in random motion.
(2)
Write in detail about your experience of various types of motion while riding a
bicycle on a road.
Ans.
When we start a bicycle we have to pedal it. This is circular motion in which
pedals of the bicycle move. Then we decide the direction and usually pick up a
linear motion. For doing so we can turn the handle of the bicycle. The wheels
of a bicycle turn in circular motion. If we go with the same speed in one
direction it will be uniform linear motion. If we increase and decrease the
speed intermittently, it will be non-uniform linear motion. Sometimes, just for
fun, we may take round turns, the motion then becomes oscillatory and circular
too.
ACTIVITY
/ EXPERIMENT :
Complete
the puzzle using words for types of motions :
(The answers are given directly.)
(1) A
spring is stretched and one end is released.
(2) A minute hand
(3) A see-saw
(4-5) Children in march-past
