TNPSC Physics – Laws of Motion Quiz 1

TNPSC Physics Quiz Laws of Motion

This TNPSC Physics Laws of Motion Quiz helps students revise important concepts such as Newton’s laws, force, inertia and momentum.

1️⃣ Sir Isaac Newton and the Laws of Motion

Sir Isaac Newton was an English physicist and mathematician who formulated the three laws of motion in the 17th century. These laws explain how objects behave when forces act on them. Newton’s laws form the foundation of classical mechanics and are widely used in engineering, physics and astronomy.

2️⃣ Newton’s First Law of Motion (Law of Inertia)

Newton’s First Law states:

An object at rest remains at rest and an object in motion continues in motion with the same speed and direction unless acted upon by an external force.

This property of resisting change in motion is called inertia.

Example:
When a moving bus stops suddenly, passengers move forward due to inertia.

3️⃣ Momentum – Product of Mass and Velocity

Momentum describes the quantity of motion possessed by an object.

Momentum = Mass × Velocity

SI Unit of Momentum: kg m/s

4️⃣ SI Unit of Force

The SI unit of force is the Newton (N).

According to Newton’s Second Law: Force = Mass × Acceleration

One Newton is defined as the force required to accelerate a 1 kg mass by 1 m/s².

5️⃣ Newton’s Second Law of Motion

Newton’s Second Law states that the rate of change of momentum is proportional to the applied force and occurs in the direction of the force.

Mathematically: F = ma

Where:

F = Force
m = Mass
a = Acceleration

This law explains how force affects motion.

6️⃣ Inertia in Daily Life

Inertia explains why passengers move forward when a bus stops suddenly. The body continues moving because it tends to maintain its state of motion.

Examples:

• Dust leaves a carpet when it is beaten
• Fruits fall when tree branches are shaken
• Passengers move backward when a bus starts suddenly

7️⃣ Newton’s Third Law of Motion

Newton’s Third Law states:

For every action there is an equal and opposite reaction.

The two forces act on different objects but have equal magnitude and opposite direction.

Examples:

• Recoil of a gun
• Rocket propulsion
• Walking on the ground

8️⃣ Inertia – Resistance to Change in Motion

Inertia is the property of matter that resists any change in its state of rest or motion.

The amount of inertia depends on the mass of the object.

Heavier objects have greater inertia.

9️⃣ Inertia and Mass

Objects with larger mass possess greater inertia because they resist changes in motion more strongly.

Example: A truck requires more force to move compared to a bicycle.

🔟 Momentum and Velocity

Momentum depends on velocity. If the velocity becomes zero, momentum also becomes zero.

For example:

A stationary object has zero momentum because its velocity is zero.

1️⃣1️⃣ Action and Reaction Forces

According to Newton’s Third Law, action and reaction forces:

• act simultaneously
• act on different objects
• are equal in magnitude
• are opposite in direction

This is why a person pushing a wall feels a force from the wall.

1️⃣2️⃣ Recoil of a Gun

Inertia is directly related to mass.

More mass → More inertia
Less mass → Less inertia

This is why heavy vehicles require more force to start or stop.

1️⃣4️⃣ Rate of Change of Momentum

Newton’s Second Law states that the rate of change of momentum of an object is equal to the applied force.

This means that if momentum changes quickly, the force applied must be large.

1️⃣5️⃣ Law of Conservation of Momentum

The Law of Conservation of Momentum states that:

The total momentum of an isolated system remains constant before and after collision.

This principle is widely used in studying collisions between objects.

1️⃣6️⃣ Types of Inertia

There are three types of inertia:

• Inertia of rest
• Inertia of motion
• Inertia of direction

These describe resistance to changes in rest, movement and direction.

1️⃣7️⃣ Reducing Force While Catching a Ball

A cricket player moves his hands backward while catching a ball.

This increases the time of impact, reducing the force experienced. This principle is related to Newton’s Second Law of Motion.

1️⃣8️⃣ Effects of Force

Force can change:

• shape of an object
• direction of motion
• speed of motion
• state of rest

Thus force plays an important role in controlling motion.

1️⃣9️⃣ SI Unit of Momentum

Momentum has the SI unit: kg m/s

It depends on both mass and velocity.

Objects with greater velocity possess greater momentum.

2️⃣0️⃣ Law of Action and Reaction

The statement:

“Every action has an equal and opposite reaction”

represents Newton’s Third Law of Motion.

This law explains many physical phenomena including walking, swimming and rocket motion.

Final Revision Tip

To answer TNPSC General Science questions correctly, focus on understanding the basic concepts rather than memorizing facts. Newton’s Laws of Motion, force, inertia and momentum are fundamental topics that frequently appear in competitive exams.

While preparing for exams, remember these key points:

• Newton formulated the three laws of motion
• Force = Mass × Acceleration (F = ma)
• Inertia depends on mass
• Momentum = Mass × Velocity
• Action and reaction forces are equal and opposite

Practicing MCQ quizzes regularly helps improve accuracy and speed. Attempt more TNPSC Physics quizzes to strengthen your understanding of motion and force.