Class: 9 Month: June Worksheet Number: 09/Sci/09/03
Subject: Science Chapter: 09 – Force and laws of
motion
Name:
____________________________________________
Section A: Exposition
Each question carries 1 mark :
1.
Name
any conservation law discussed in this chapter.
2.
What
type of quantity is momentum? Scalar or vector?
3.
What
is the momentum of a body at rest?
4.
Which
law will you use to explain the following cases;
(i)
An
inflated balloon flies off in the air, if its knot is untied.
(ii)
When
a shell is fired from a canon, the canon experiences a backward jerk.
5.
Which
physical quantity is related with rate of change of momentum?
Each
question carries 5 marks :
6.
Suppose two balls A and B of masses mA
and mB are travelling in the
same direction along a straight line at different velocities uA
and uB, respectively
Let
uA is greater than
uB so ball A hits
ball B at back
Suppose balls A and B
after the collision, moves in the same direction with velocities vAand
vB
For
this collision between the balls
(i)
State
the law of conservation of momentum.
(ii)
Write
its mathematical formulation.
(iii)
Derive the mathematical formulation for
it.
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Class: 9 Month: June
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Worksheet Number: 09/Sci/09/03
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Subject: Science
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Chapter: 09 – Force and laws of
motion
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Section B:
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Extended
Exposition
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Each question carries 1 mark :
7.
Question i to ii refers to
collisions between a car and small pickup. For each description, choose an
answer from the given possibilities (A - J) that best describes the
magnitude of the forces between the car and the pickup.
A
The pickup exerts a larger force on the car than the
car exerts on the small pickup.
B
The car exerts a larger force on the pickup than the
small pickup exert on the car.
C
Neither exerts a force on the other
one; the car gets smashed simply because it is in the way of the pickup.
D
The pickup exerts a force on the car but the car
doesn’t exert a force on the pickup.
E
The pickup exerts the same amount of
force on the car as the car exerts on the pickup. F Enough information
is not given to pick one of the answers from above.
J None of the answers above describes the
situation correctly.
The pickup and the car has the
same weight.
i
Both the pickup and the car are
moving at the same speed when they collide. Which choice describes the forces?
ii The pickup is standing still when the car
hits it. Which choice describes the forces?
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Class: 9 Month: June Worksheet Number: 09/Sci/09/03
Subject: Science Chapter: 09 – Force and laws of
motion
8.
Question i to iii refers
to collisions between a car and truck. For each description, choose an answer
from the given possibilities (A - J) that best describes the magnitude
of the forces between the car and the truck.
A
The truck exerts a larger force on the car than the
car exerts on the truck.
B
The car exerts a larger force on the truck than the
truck exert on the car.
C
Neither exerts a force on the other
one; the car gets smashed simply because it is in the way of the truck.
D
The truck exerts a force on the car but the car
doesn’t exert a force on the truck.
E
The truck exerts the same amount of
force on the car as the car exerts on the truck.
F Enough
information is not given to pick one of the answers from above.
J None
of the answers above describes the situation correctly.
The truck is much heavier than
the truck.
i.
They are both moving at the same
speed when they collide. Which choice describes the forces?
ii.
The car is moving much faster than
the heavier truck when they collide. Which choice describes the forces?
iii.
The heavier truck is standing still when the car
hits it. Which choice describes the forces?
Section
C: Interpretation &
Reasoning
Each question carries 1 mark :
9.
A gun is about to fire. What is the
total momentum of the bullet and the gun before firing? Give reason.
10.
Which will have more momentum; a 5 kg
body at rest or a 2 kg body in motion? Give reason.
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Class: 9 Month: June Worksheet Number: 09/Sci/09/03
Subject: Science Chapter: 09 – Force and laws of
motion
Each question carries 2 marks :
11.
A bicycle and a truck are moving towards
one another with same speed. Which of the two will have to apply more force to
stop in order to void collision and why?
Section
D: Problem Solving
Each question carries 2 marks :
12.
The
velocity of a speeding motorcycle is doubled. What will be change in its
momentum?
13.
From a rifle of mass 4kg, a bullet of
mass 50g is fired with an initial velocity of 35m/s. calculate the initial
recoil velocity of the rifle.
Each
question carries 3 marks :
14.
A force of mass 12 N starts acting on a
body kept at rest. Find the momentum of the body at 1 s, 2 s and 5 s after the
force starts acting.
15.
A body of mass 300 g kept at rest breaks
into two parts due to internal explosion. One of the mass 200 g moves with a
speed of 12 m/s towards forward direction. What will be the velocity (both
magnitude and direction) of the other part?
16.
Two balls of masses 100 g and 25 g move
in opposite directions towards each other with velocities of 50 cm/s and 75
cm/s respectively. Calculate their resultant velocity on collision, if they
stick together.
Each
question carries 5 mark :
17.
A large truck and a car, both moving
with a velocity v, have a head –on collision and both of these come to a halt
after that. If the collision lasts for 1 s:
A
Which vehicle experiences the grater force of
impact?
B
Which vehicle experiences the grater
change in momentum?
C
Which vehicle experiences the grater
acceleration?
D
Why is the car likely to suffer more
damage than the small pickup?
18.
A bowler throws a cricket ball of mass
200 g with a velocity 30 m/s towards the batsman. Batsman strikes the ball with
the velocity 45 m/s in just the opposite direction.
A
What is the initial momentum of the ball (Magnitude
and direction both)
B
What is the final momentum of the
ball (Magnitude and direction both)
C
What is the change in the momentum of the ball (Magnitude and direction
both)
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Class: 9 Month: June
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Worksheet Number: 09/Sci/09/03
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Subject: Science
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Chapter: 09 – Force and laws of
motion
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