30 important multiple-choice questions (MCQs) on the topic "Law of Motion" for Class 12 students, covering concepts related to Newton's laws, inertia, force, momentum, friction, and applications:

 

Answers are given Below

 

When a bus starts suddenly, the passengers are pushed backward. This illustrates which law of motion?
a) Newton’s First Law
b) Newton’s Second Law
c) Newton’s Third Law
d) Law of Gravitation

The property of a body to resist a change in its state of motion is called:
a) Momentum
b) Inertia
c) Force
d) Acceleration

Newton’s Second Law of Motion states that force is equal to:
a) Mass × velocity
b) Mass × acceleration
c) Momentum × time
d) Acceleration ÷ mass

According to Newton’s Third Law of Motion, to every action there is:
a) No reaction
b) An equal and opposite reaction
c) A larger reaction
d) A smaller reaction

Which of these physical quantities is conserved due to Newton's Third Law?
a) Energy
b) Velocity
c) Momentum
d) Force

Inertia of rest means:
a) A body remains at rest unless an external force is applied
b) A body moves spontaneously
c) A body changes its velocity automatically
d) None of the above

If an object moves with constant velocity, the net force acting on it is:
a) Positive
b) Negative
c) Zero
d) Infinity

Force is the rate of change of:
a) Displacement
b) Velocity
c) Momentum
d) Energy

A force of 10 N acts on a body of mass 2 kg. The acceleration produced is:
a) 20 m/s²
b) 5 m/s²
c) 0.2 m/s²
d) 10 m/s²

Action and reaction forces act:
a) On the same body
b) On different bodies
c) In the same direction
d) Only on stationary bodies

Why do passengers lean forward when a bus suddenly stops?
a) Due to inertia of motion
b) Due to external force
c) Due to friction
d) Due to gravity

The SI unit of force is:
a) Joule
b) Newton
c) Pascal
d) Watt

The momentum of a body is given by the product of:
a) Mass and velocity
b) Force and time
c) Mass and acceleration
d) Velocity and acceleration

Which law explains the motion of a rocket?
a) Newton’s First Law
b) Newton’s Second Law
c) Newton’s Third Law
d) Law of Universal Gravitation

What force acts on a body moving on a rough surface opposing its motion?
a) Gravitational force
b) Frictional force
c) Electrostatic force
d) Magnetic force

A truck collides with a car. According to Newton’s Third Law, the forces exerted are:
a) Equal and opposite
b) Equal and in the same direction
c) Different magnitudes
d) Zero

The acceleration produced in a body is directly proportional to:
a) Mass
b) Force
c) Velocity
d) Displacement

The time rate of change of momentum is equal to:
a) Force
b) Energy
c) Impulse
d) Power

Which of these scenarios shows an example of Newton’s First Law?
a) A ball thrown upward comes down
b) A stationary book remains at rest on the table
c) A car accelerating on a highway
d) A person jumping from a boat

The law of motion that helps to measure force in dynamics is:
a) First law
b) Second law
c) Third law
d) Law of conservation of energy

What happens when a string tied to a mass is jerked suddenly downward?
a) The upper string breaks
b) The lower string breaks
c) Mass moves up
d) Nothing happens

The force responsible for the movement in swimming is explained by:
a) First law
b) Second law
c) Third law
d) None of these

When you get down from a running bus, you tend to fall forward due to:
a) Inertia of rest
b) Inertia of motion
c) Friction
d) Acceleration

The unit of momentum is:
a) kg·m/s
b) N·s
c) m/s²
d) kg·m²/s

Which law states that “The acceleration of an object is directly proportional to the net force applied and inversely proportional to its mass”?
a) First law
b) Second law
c) Third law
d) Law of conservation of momentum

What type of friction acts when an object just starts moving?
a) Kinetic friction
b) Static friction
c) Rolling friction
d) Fluid friction

Which of the following is NOT a law of motion formulated by Newton?
a) Law of inertia
b) Law of acceleration
c) Law of relativity
d) Law of action-reaction

Velocity changes when:
a) A net external force acts on the body
b) Body is at rest
c) No forces act on the body
d) Body moves with constant speed

The force acting normal to the surface between two objects in contact is called:
a) Frictional force
b) Tension force
c) Normal force
d) Gravitational force

If a book is placed on a table, the action and reaction pair are:
a) Book pushes table down, table pushes book up
b) Book pushes air, air pushes book
c) Book pushes table up, table pushes book down
d) No pair exists

 

correct answer and a brief explanation:

 

When a bus starts suddenly, the passengers are pushed backward. This illustrates which law of motion?
Answer: a) Newton’s First Law
Explanation: The passengers tend to remain in their original state (at rest) due to inertia when the bus moves forward suddenly.

The property of a body to resist a change in its state of motion is called:
Answer: b) Inertia
Explanation: Inertia is the tendency of an object to resist any change in its motion or rest.

Newton’s Second Law of Motion states that force is equal to:
Answer: b) Mass × acceleration
Explanation: Force causes acceleration of a body and is proportional to mass and acceleration (F=ma).

According to Newton’s Third Law of Motion, to every action there is:
Answer: b) An equal and opposite reaction
Explanation: Forces always come in pairs acting on two different bodies.

Which of these physical quantities is conserved due to Newton's Third Law?
Answer: c) Momentum
Explanation: Action-reaction pairs exert equal and opposite impulses keeping total momentum conserved.

Inertia of rest means:
Answer: a) A body remains at rest unless an external force is applied
Explanation: A resting object resists change and stays at rest unless acted upon.

If an object moves with constant velocity, the net force acting on it is:
Answer: c) Zero
Explanation: Zero net force means no change in velocity according to Newton’s First Law.

Force is the rate of change of:
Answer: c) Momentum
Explanation: Force equals the time rate of change of momentum.

A force of 10 N acts on a body of mass 2 kg. The acceleration produced is:
Answer: b) 5 m/s²
Explanation: a=Fm=102=5 m/s2a = \frac{F}{m} = \frac{10}{2} = 5 \, m/s^2a=mF=210=5m/s2.

Action and reaction forces act:
Answer: b) On different bodies
Explanation: They act on two different interacting bodies, never the same.

Why do passengers lean forward when a bus suddenly stops?
Answer: a) Due to inertia of motion
Explanation: Passengers tend to continue moving forward even if the bus stops suddenly.

The SI unit of force is:
Answer: b) Newton
Explanation: Named after Isaac Newton, it is the SI unit of force.

The momentum of a body is given by the product of:
Answer: a) Mass and velocity
Explanation: Momentum p=m×vp = m \times vp=m×v.

Which law explains the motion of a rocket?
Answer: c) Newton’s Third Law
Explanation: The backward expulsion of gases causes forward thrust (action-reaction).

What force acts on a body moving on a rough surface opposing its motion?
Answer: b) Frictional force
Explanation: Friction opposes relative motion between surfaces in contact.

A truck collides with a car. According to Newton’s Third Law, the forces exerted are:
Answer: a) Equal and opposite
Explanation: The forces on both vehicles are equal in magnitude and opposite in direction.

The acceleration produced in a body is directly proportional to:
Answer: b) Force
Explanation: From F=maF = maF=ma, acceleration is proportional to force.

The time rate of change of momentum is equal to:
Answer: a) Force
Explanation: Force is defined as the derivative of momentum with respect to time.

Which of these scenarios shows an example of Newton’s First Law?
Answer: b) A stationary book remains at rest on the table
Explanation: The book remains at rest unless acted upon by a force.

The law of motion that helps to measure force in dynamics is:
Answer: b) Second law
Explanation: It relates force to mass and acceleration quantitatively.

What happens when a string tied to a mass is jerked suddenly downward?
Answer: b) The lower string breaks
Explanation: The lower string experiences greater tension due to sudden jerk motion.

The force responsible for the movement in swimming is explained by:
Answer: c) Third law
Explanation: The swimmer pushes water backward; water pushes swimmer forward.

When you get down from a running bus, you tend to fall forward due to:
Answer: b) Inertia of motion
Explanation: Your body continues moving forward when the bus stops.

The unit of momentum is:
Answer: a) kg·m/s
Explanation: Momentum unit is mass times velocity.

Which law states that “The acceleration of an object is directly proportional to the net force applied and inversely proportional to its mass”?
Answer: b) Second law
Explanation: This is Newton’s Second Law.

What type of friction acts when an object just starts moving?
Answer: b) Static friction
Explanation: Static friction must be overcome to start motion.

Which of the following is NOT a law of motion formulated by Newton?
Answer: c) Law of relativity
Explanation: Law of relativity was formulated by Einstein, not Newton.

Velocity changes when:
Answer: a) A net external force acts on the body
Explanation: Force causes acceleration, changing velocity.

The force acting normal to the surface between two objects in contact is called:
Answer: c) Normal force
Explanation: It acts perpendicular to the surfaces in contact.

If a book is placed on a table, the action and reaction pair are:
Answer: a) Book pushes table down, table pushes book up
Explanation: Action and reaction forces act on different bodies.