Exercise class 9 science chapter 1 laws of motion । exercise laws of motion । Std 9 science lesson 1
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3 سال پیش
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Exercise class 9 science chapter
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1. Match the first column with appropriate entries in the second and third columns
and remake the table.
S. No.
Column 1
Column 2
Column 3
1
Negative
acceleration
The velocity of the object remains constant
A car, initially at rest
reaches a velocity of 50 km/hr in 10 seconds
2
Positive
acceleration
The velocity of
the object decreases
A vehicle is moving with a
velocity of 25 m/s
3
Zero
acceleration
The velocity of the
object increases
A vehicle moving with the velocity of
10 m/s, stops after 5 seconds.
2. Clarify the differences
A. Distance and displacement
B. Uniform and non-uniform motion
Complete the following table.
u (m/s)
a (m/s2)
t (sec)
v = u + at (m/s)
2
4
3
-
-
5
2
20
u (m/s)
a (m/s2)
t (sec)
5
12
3
-
7
-
4
92
u (m/s)
a (m/s2)
s (m)
v 2
= u2
+ 2as (m/s)2
4
3
-
8
-
5
8.4
10
4. Complete the sentences and explain
them.
a. The minimum distance between
the start and finish points of the
motion of an object is called the
……….. of the object.
b. Deceleration is -------- acceleration
c. When an object is in uniform
circular motion, its ………
changes at every point.
d. During collision ......….. remains
constant.
e. The working of a rocket depends
on Newton’s ….…. law of motion.
5. Give scientific reasons.
a. When an object falls freely to the
ground, its acceleration is uniform.
b. Even though the magnitudes of
action force and reaction force are
equal and their directions are
opposite, their effects do not get
cancelled.
c. It is easier to stop a tennis ball as
compared to a cricket ball, when
both are travelling with the same
velocity.
d. The velocity of an object at rest is
considered to be uniform.
6. Take 5 examples from your
surroundings and give explanation
based on Newtons laws of motion.
7. Solve the following examples.
a) An object moves 18 m in the first
3 s, 22 m in the next 3 s and 14 m in
the last 3 s. What is its average
speed?
(Ans: 6 m/s)
b) An object of mass 16 kg is moving
with an acceleration of 3 m/s2
.
Calculate the applied force. If the
same force is applied on an object of
mass 24 kg, how much will be the
acceleration? (Ans: 48 N, 2 m/s2)
c) A bullet having a mass of 10 g and
moving with a speed of 1.5 m/s,
penetrates a thick wooden plank of
mass 900 g. The plank was initially
at rest. The bullet gets embedded in
the plank and both move together.
Determine their velocity.
(Ans: 0.15 m/s)
d) A person swims 100 m in the first
40 s, 80 m in the next 40 s and 45 m
in the last 20 s. What is the average
speed? (Ans: 2.25 m/s2)
Project:
Obtain information about
commonly used gadgets or devices
which are based on the principles
of Newton’s laws of motion.
1. Match the first column with appropriate entries in the second and third columns
and remake the table.
S. No.
Column 1
Column 2
Column 3
1
Negative
acceleration
The velocity of the object remains constant
A car, initially at rest
reaches a velocity of 50 km/hr in 10 seconds
2
Positive
acceleration
The velocity of
the object decreases
A vehicle is moving with a
velocity of 25 m/s
3
Zero
acceleration
The velocity of the
object increases
A vehicle moving with the velocity of
10 m/s, stops after 5 seconds.
2. Clarify the differences
A. Distance and displacement
B. Uniform and non-uniform motion
Complete the following table.
u (m/s)
a (m/s2)
t (sec)
v = u + at (m/s)
2
4
3
-
-
5
2
20
u (m/s)
a (m/s2)
t (sec)
5
12
3
-
7
-
4
92
u (m/s)
a (m/s2)
s (m)
v 2
= u2
+ 2as (m/s)2
4
3
-
8
-
5
8.4
10
4. Complete the sentences and explain
them.
a. The minimum distance between
the start and finish points of the
motion of an object is called the
……….. of the object.
b. Deceleration is -------- acceleration
c. When an object is in uniform
circular motion, its ………
changes at every point.
d. During collision ......….. remains
constant.
e. The working of a rocket depends
on Newton’s ….…. law of motion.
5. Give scientific reasons.
a. When an object falls freely to the
ground, its acceleration is uniform.
b. Even though the magnitudes of
action force and reaction force are
equal and their directions are
opposite, their effects do not get
cancelled.
c. It is easier to stop a tennis ball as
compared to a cricket ball, when
both are travelling with the same
velocity.
d. The velocity of an object at rest is
considered to be uniform.
6. Take 5 examples from your
surroundings and give explanation
based on Newtons laws of motion.
7. Solve the following examples.
a) An object moves 18 m in the first
3 s, 22 m in the next 3 s and 14 m in
the last 3 s. What is its average
speed?
(Ans: 6 m/s)
b) An object of mass 16 kg is moving
with an acceleration of 3 m/s2
.
Calculate the applied force. If the
same force is applied on an object of
mass 24 kg, how much will be the
acceleration? (Ans: 48 N, 2 m/s2)
c) A bullet having a mass of 10 g and
moving with a speed of 1.5 m/s,
penetrates a thick wooden plank of
mass 900 g. The plank was initially
at rest. The bullet gets embedded in
the plank and both move together.
Determine their velocity.
(Ans: 0.15 m/s)
d) A person swims 100 m in the first
40 s, 80 m in the next 40 s and 45 m
in the last 20 s. What is the average
speed? (Ans: 2.25 m/s2)
Project:
Obtain information about
commonly used gadgets or devices
which are based on the principles
of Newton’s laws of motion.
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