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Class 9 Physics Chapter 3


Updated: 19 Oct 2023

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Class 9 Physics Chapter 3 is about Dynamics”. This article includes topics such as Definition of Dynamics, Force, Newton’s Law of Motion, Inertia, Newton’s First Law of Motion, Newton’s Second Law of Motion, Newton’s Third Law of Motion, Mass, Weight, Linear Momentum, Force and Change in Momentum, Isolated System, Change of Momentum and Collison’s, Change of Momentum and Expulsive Forces, Rocket Propulsion and Thrust, Friction, Normal Force, Types of Frictional Forces, Static Friction, Kinetic Friction, Coefficient Friction, Advantages of Friction, Disadvantages of Friction, Rolling Friction, Methods of Reducing Friction, Tension, Uniform Circular Motion, Centripetal Acceleration and Centripetal Force.

Class 9 Physics Chapter 3 Notes

Dynamics Notes

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Class 9 Physics Chapter 3 Notes

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Class 9 Physics Chapter 3 SLO Notes

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Class 9 Physics Chapter 3 SLO Notes

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Class 9 Physics Chapter 3 MCQs

Dynamics

1 The branch of mechanics which deals with the study of motion by analyzing the cause of motion is called
(a) Kinematics
(b) Dynamics
(c) Optics
(d) Thermodynamics
Show Answer

Dynamics


Force

2 A push or a pull on an object is called
(a) Work
(b) Energy
(c) Force
(d) Momentum
Show Answer

Force


3 Force is a …………. quantity.
(a) Scalar
(b) Vector
(c) Tensor
(d) None of these
Show Answer

Vector


Vector 4 What is the unit of force in the SI system?
(a) Joule
(b) Pascal
(c) Newton
(d) Watt
Show Answer

Newton


5 What is the symbol of force?
(a) F
(b) M
(c) A
(d) V
Show Answer

F


6 Force is a vector quantity. What does this mean?
(a) It has magnitude only
(b) It has direction only
(c) It has both magnitude and direction
(d) It has neither magnitude nor direction
Show Answer

It has both magnitude and direction


7 How can Newton (N) be expressed in terms of fundamental units?
(a) Nm^2/kg
(b) kg/m^2
(c) kgm/s^2
(d) N/kg
Show Answer

kgm/s^2


8 Which of the following is an example of a contact force?
(a) Gravitational force
(b) Magnetic force
(c) Frictional force
(d) Electric force
Show Answer

Frictional force


9 Which of the following is an example of a non-contact force?
(a) Frictional force
(b) Magnetic force
(c) Normal force
(d) Applied force
Show Answer

Magnetic force


10 In which book did Newton publish his laws of motion?
(a) Physics
(b) Elements
(c) Optics
(d) Philosophiæ Naturalis Principia Mathematica
Show Answer

Philosophiæ Naturalis Principia Mathematica


To Download Complete Notes of Physics Notes 9 Class, Click on the given link.

Newton’s Law of Motion

11 Law of motion was presented by:
(a) Einstein
(b) Newton
(c) Galileo
(d) None of these
Show Answer

Newton


Newton’s First Law of Motion

Inertia

12 Newton’s first law of motion is also known as the law of:
(a) Acceleration
(b) Force and motion
(c) Inertia
(d) Interaction
Show Answer

Inertia


13 The property of a body due to which it retain its state is called
(a) Inertia
(b) Force
(c) Work
(d) Energy
Show Answer

Inertia


14 A physical quantity which moves or tends to move, stops or tends to stop a moving object is called
(a) Inertia
(b) Force
(c) Momentum
(d) Work
Show Answer

Force


15 The quantitative measure of inertia is called
(a) Force
(b) Inertia
(c) Mass
(d) Time
Show Answer

Mass


16 Law of inertia is actually the …………. Law of motion
(a) 1^{st}
(b) 2^{nd}
(c) 3^{rd}
(d) None of these
Show Answer

1^{st}


17 The SI unit of inertia is
(a) Second
(b) Kilogram
(c) Meter
(d) Ampere
Show Answer

Kilogram


Newton’s Second Law of Motion

18. The acceleration of an object is directly proportional to force and inversely proportional to the mass, is the statement of
(a) 1^{st} \ law
(b) 2^{nd} \ law
(c) 3^{rd} \ law
(d) None of these
Show Answer

2^{nd} \ law


19 When force is applied on a body, ………………… is produced in the body?
(a) Energy
(b) Force
(c) Acceleration
(d) None of these
Show Answer

Acceleration


20 The formula F=ma represents:
(a) Newton’s first law
(b) Newton’s second law
(c) Newton’s third law
(d) None of these
Show Answer

Newton’s second law


21 The acceleration produced in a body is always in the direction of:
(a) Applied force
(b) Momentum
(c) Mass
(d) Energy
Show Answer

Applied force


22 If the mass of the body is doubled while keeping the force constant then acceleration will be:
(a) Double
(b) Triple
(c) One half
(d) None of these
Show Answer

One half


23 If the force is doubled while keeping the mass constant then acceleration will be:
(a) Double
(b) Triple
(c) One half
(d) None of these
Show Answer

Double


24 What will be the acceleration if applied force is 10 N on an object of mass 5 kg?
(a) 1 m/s^2
(b) 2 m/s^2
(c) 3 m/s^2
(d) 4 m/s^2
Show Answer

2 m/s^2


25 What will be the force produced an acceleration of 3 m/s^2 in an object of mass 5 kg?
(a) 5 N
(b) 10 N
(c) 15 N
(d) 20 N
Show Answer

15 N


Newton’s Third Law of Motion

26 According to Newton’s third law of motion, if object A exerts a force on object B, the reaction force is:
(a) Zero
(b) Perpendicular to the force on object A
(c) In the opposite direction to the force on object A
(d) In the same direction as the force on object A
Show Answer

In the opposite direction to the force on object A


27 Action and reaction are equal in magnitude but opposite in direction is known as …………. Law of motion.
(a) 1st
(b) 2nd
(c) 3rd
(d) None of these
Show Answer

3rd


28 The mathematical expression for Newton third law is:
(a) F_A= - F_B
(b) F = ma
(c) F_A = F_B
(d) None of these
Show Answer

F_A= - F_B


29 The negative sign in Newton third law of motion indicates:
(a) F_A is parallel to F_B
(b) F_A is perpendicular to F_B
(c) F_A is in opposite direction to F_B
(d) F_A is in same direction to F_B
Show Answer

F_A is in opposite direction to F_B


30 Walking on the road is an example of:
(a) Newton’s first law
(b) Newton’s second law
(c) Newton’s third law
(d) None of these
Show Answer

Newton’s third law


31 Weight is the force experienced by an object due to its:
(a) Mass
(b) volume
(c) density
(d) speed
Show Answer

Mass


Mass and Weight

Weight

32 What is the symbol for weight?
(a) F
(b) M
(c) N
(d) W
Show Answer

W


33 The weight of an object varies from place to place because:
(a) The mass of the object changes
(b) The acceleration due to gravity changes
(c) The object’s volume changes
(d) None of these
Show Answer

The acceleration due to gravity changes


34 What is the unit of weight in the SI system?
(a) Newton
(b) Kilogram
(c) Pound
(d) Watt
Show Answer

Newton


35 Weight is a……………. quantity.
(a) Scalar
(b) Vector
(c) Tensor
(d) All of these
Show Answer

Vector


36 What is the formula for calculating weight (W) of an object?
(a) W = mg
(b) W = mv
(c) W = ma
(d) None of these
Show Answer

W = mg


37 Calculate the weight of an object with a mass of 5 kg (take \ g = 9.81 m/s^2).
(a) 49.05 N
(b) 14.29 N
(c) 45.67 N
(d) 20.21 N
Show Answer

49.05 N


38 The weight of the body of mass 10 kg on earth surface is:
(a) 32 N
(b) 50 N
(c) 98 N
(d) 102 N
Show Answer

98 N


39 The ………….. of the body is always acting towards the center of the earth.
(a) Mass
(b) Weight
(c) Force
(d) All of these
Show Answer

Weight


40 The force with which the object is attracted toward the center of the earth is:
(a) Mass
(b) Electric force
(c) Magnetic force
(d) Weight
Show Answer

Weight


41 The physical quantity that varies from place to place is:
(a) Mass
(b) Weight
(c) Both A and B
(d) None of these
Show Answer

Weight


42 What is the value of acceleration due to gravity (g) on Earth’s surface?
(a) 1.62 m/s^2
(b) 5.33 m/s^2
(c) 24.7 m/s^2
(d) 9.8 m/s^2
Show Answer

9.8 m/s^2


43 What is the value of acceleration due to gravity (g) on the surface of Moon?
(a) 1.62 m/s^2
(b) 5.33 m/s^2
(c) 24.7 m/s^2
(d) 9.8 m/s^2
Show Answer

1.62 m/s^2


Mass

44 The amount of matter in an object is called
(a) Weight
(b) Force
(c) Mass
(d) Momentum
Show Answer

Mass


45 What is the symbol for mass?
(a) M
(b) W
(c) F
(d) S
Show Answer

M


46 What is the unit of mass in the SI system?
(a) Newton
(b) Kilogram
(c) Pound
(d) Watt
Show Answer

Kilogram


47 Mass is a ……………. Quantity.
(a) Scalar
(b) Vector
(c) Tensor
(d) All of these
Show Answer

Scalar


48 The physical quantity that remains same everywhere is:
(a) Mass
(b) Weight
(c) Both A and B
(d) None of these
Show Answer

Mass


Linear Momentum

49 The product of an object’s mass and velocity is called:
(a) Force
(b) Weight
(c) Linear momentum
(d) None of these
Show Answer

Linear momentum


50 The quantity of motion in a body is called
(a) Force
(b) Weight
(c) Linear momentum
(d) None of these
Show Answer

Linear momentum


51 What is the symbol for linear momentum?
(a) L
(b) M
(c) V
(d) P
Show Answer

P


52 What is the unit of linear momentum?
(a) kg m/s
(b) Ns
(c) m/s
(d) Both (a) and (b)
Show Answer

Both (a) and (b)


53 What is the formula for calculating linear momentum (P) of an object?
(a) P = mv
(b) P = ma
(c) P = mg
(d) All of these
Show Answer

P = mv


54 Linear momentum is a ………… quantity.
(a) Scalar
(b) Vector
(c) Tensor
(d) All of these
Show Answer

Vector


55 Calculate the linear momentum of an object with a mass of 2 kg and a velocity of 3 m/s .
(a) 5 kg m/s
(b) 8 kg m/s
(c) 6 kg m/s
(d) 1 kg m/s
Show Answer

6 kg m/s


56 The rate of change in momentum is called
(a) Mass
(b) Weight
(c) Force
(d) Energy
Show Answer

Force


Isolated System

57 A system with no external forces acting on it is said to be:
(a) Isolated system
(b) Opened system
(c) Closed system
(d) None of these
Show Answer

Isolated system


58 The total momentum of an isolated system is constant, is stated by:
(a) Law of conservation of energy
(b) Law of conservation of mass
(c) Law of conservation of momentum
(d) All of these
Show Answer

Law of conservation of momentum


Change of Momentum and Collisions

59 An event during which particles come close to each other and interact by means of a force is called
(a) Collision
(b) Explosion
(c) Interaction
(d) None of these
Show Answer

Collision


Change of Momentum and Expulsive Forces

60 An event during which particles move away from each other after collision is called
(a) Collision
(b) Explosion
(c) Interaction
(d) None of these
Show Answer

Explosion


Friction

61 The force that opposes motion between two surfaces in contact is called
(a) Weight
(b) Momentum
(c) Friction
(d) Tension
Show Answer

Friction


62 What is the symbol for friction?
(a) f
(b) T
(c) F
(d) g
Show Answer

f


63 What is the unit of friction in the SI system?
(a) Newton
(b) Kilogram
(c) Pascal
(d) Watt
Show Answer

Newton


64 Friction is a …………….. Quantity.
(a) Scalar
(b) Vector
(c) Tensor
(d) None of these
Show Answer

Vector


65 In which direction does friction act when an object moves on a surface?
(a) In the same direction as motion
(b) Opposite to the direction of motion
(c) Perpendicular to the direction of motion
(d) None of these
Show Answer

Opposite to the direction of motion


Types of Frictional Forces

Static Friction

66 Friction experienced by an object at rest:
(a) Static friction
(b) Kinetic friction
(c) Sliding friction
(d) Rolling friction
Show Answer

Static friction


67 The maximum value of static friction is known as
(a) Static friction
(b) Kinetic friction
(c) Limiting friction
(d) Sliding friction
Show Answer

Limiting friction


Kinetic Friction

68 Friction experienced by an object in motion:
(a) Static friction
(b) Kinetic friction
(c) Sliding friction
(d) Rolling friction
Show Answer

Kinetic friction


69 Which condition is true?
(a) f_s > f_k
(b) f_s < f_k
(c) f_s = f_k
(d) None of these
Show Answer

f_s > f_k


Normal Force

70 A contact force perpendicular to the surface of contact objects is:
(a) Friction
(b) Normal force
(c) Tension
(d) Centripetal force
Show Answer

Normal force


71 What is the symbol for normal force:
(a) f
(b) T
(c) FN
(d) All of these
Show Answer

FN


72 What is the unit of normal force in the SI system?
(a) Newton
(b) Kilogram
(c) Pascal
(d) Watt
Show Answer

Newton


73 The ratio of the frictional force to the normal force is:
(a) Tension
(b) Coefficient of friction
(c) Normal force
(d) None of these
Show Answer

Coefficient of friction


Coefficient Friction

74 What is the unit of coefficient of friction in the SI system?
(a) Newton
(b) Kilogram
(c) Pascal
(d) Dimensionless (no unit)
Show Answer

Dimensionless (no unit)


75 What is the symbol for the coefficient of friction?
(a) C
(b) F
(c) \mu
(d) W
Show Answer

\mu


Sliding Friction

76 Friction experienced by an object in motion along a surface is:
(a) Sliding friction
(b) Rolling friction
(c) Tension
(d) None of these
Show Answer

Sliding friction


Rolling Friction

77 Friction experienced by a rolling object is:
(a) Sliding friction
(b) Rolling friction
(c) Tension
(d) None of these
Show Answer

Rolling friction


Methods of Reducing Friction

78 What is one way to reduce friction between two surfaces in contact?
(a) Increase the normal force between the surfaces
(b) Increase the mass of the objects
(c) Apply a lubricant between the surfaces
(d) None of these
Show Answer

Apply a lubricant between the surfaces


Tension

79 The force exerted by a rope, string, or cable on an object which is attached with it, is called
(a) Friction
(b) Tension
(c) Normal force
(d) All of these
Show Answer

Tension


80 ……………….. is a pulling force.
(a) Friction
(b) Tension
(c) Normal force
(d) All of these
Show Answer

Tension


81 What is the symbol for tension?
(a) T
(b) N
(c) F
(d) L
Show Answer

T


82 What is the unit of tension in the SI system?
(a) Newton
(b) Kilogram
(c) Pascal
(d) Watt
Show Answer

Newton


83 When is tension taken as positive?
(a) When the rope is being pulled up
(b) When the rope is at rest
(c) When the rope is being pulled down
(d) None of these
Show Answer

When the rope is being pulled up


84 When is tension taken as negative?
(a) When the rope is being pulled up
(b) When the rope is at rest
(c) When the rope is being pulled down
(d) None of these
Show Answer

When the rope is being pulled down


85 A machine consisting of two different masses connected by a string running over a pulley is
(a) Washing machine
(b) Atwood machine
(c) Juicer machine
(d) None of these
Show Answer

Atwood machine


Uniform Circular Motion

86 Motion at a constant speed along a circular path is:
(a) Uniform circular motion
(b) Non-uniform circular motion
(c) Motion in a straight line
(d) All of these
Show Answer

Uniform circular motion


87 Motion at varying speeds along a circular path is:
(a) Uniform circular motion
(b) Non-uniform circular motion
(c) Motion in a straight line
(d) All of these
Show Answer

Non-uniform circular motion


Centripetal Acceleration

88 Acceleration directed towards the center of a circle is
(a) Acceleration
(b) Centripetal acceleration
(c) Centrifugal acceleration
(d) Angular acceleration
Show Answer

Centripetal acceleration


89 What is the symbol for centripetal acceleration?
(a) A
(b) c
(c) a_c
(d) A_C
Show Answer

a_c


90 What is the unit of centripetal acceleration in the SI system?
(a) m/s^2
(b) m/s
(c) Ns
(d) kg
Show Answer

m/s^2


91 What is the formula for calculating the magnitude of centripetal acceleration (a_c) of an object moving in a circle of radius (r) at a speed (v) ?
(a) a_c = r/v
(b) a_c = v/r
(c) a_c = v^2/r
(d) a_c = r^2/v
Show Answer

a_c = v^2/r


92 Calculate the magnitude of centripetal acceleration of an object moving in a circle of radius 2 meters at a speed of 3 m/s .
(a) 1 m/s^2
(b) 6 m/s^2
(c) 4.5 m/s^2
(d) 9 m/s^2
Show Answer

4.5 m/s^2


93 Calculate the magnitude of centripetal acceleration of an object moving in a circle of radius 5 meters at a speed of 5 m/s .
(a) 5 m/s^2
(b) 6 m/s^2
(c) 25 m/s^2
(d) 9 m/s^2
Show Answer

5 m/s^2


Centripetal Force

94 The force that keeps an object moving in a circular path is
(a) Friction
(b) Centripetal force
(c) Centrifugal force
(d) None of these
Show Answer

Centripetal force


95 What is the symbol for centripetal force?
(a) F_c
(b) f
(c) C
(d) L
Show Answer

F_c


96 What is the unit of centripetal force in the SI system?
(a) Newton
(b) Kilogram
(c) Pascal
(d) Watt
Show Answer

Newton


97 What is the formula for calculating magnitude of centripetal force acting on an object moving in a circle of mass (m) at a speed (v) with a radius (r) ?
(a) F_C = mv
(b) F_C = ma
(c) F_C = mv^2/r
(d) F_C = m/r
Show Answer

F_C = mv^2/r


98 Calculate the magnitude of centripetal force acting on an object with a mass of 10 kg moving in a circle of radius 5 \ meters at a speed of 8 m/s .
(a) 200 N
(b) 40 N
(c) 32 N
(d) 128 N
Show Answer

128 N


99 The force that keeps planets in their orbits around the sun is
(a) Friction
(b) Centripetal force
(c) Centrifugal force
(d) None of these
Show Answer

Centripetal force


100 The force that pulls an object away from the center of a circle is
(a) Friction
(b) Centripetal force
(c) Centrifugal force
(d) None of these
Show Answer

Centrifugal force


Physics Class 9 MCQs (All Chapters)


jawad khalil

jawad khalil

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