TNPSC Physics Laws of Motion Quiz 3 with Answers and Explanation

Concept Booster For this Quiz –Detailed Explanation & Quick Revision

This Concept Booster on TNPSC Physics Laws of Motion provides a clear and detailed explanation of important topics such as Newton’s laws, force, momentum, impulse, and friction. These concepts are frequently asked in TNPSC exams through both direct and application-based questions.

By going through this section, you will gain a strong understanding of real-life applications and key formulas, helping you answer questions quickly and accurately in the exam.

👉 Use this as a quick revision guide before attempting the quiz or during last-minute preparation.

1. Newton’s Laws of Motion (Core Concept)

✅ Newton’s First Law (Law of Inertia)

A body remains at rest or continues in uniform motion unless acted upon by an external force.

👉 This explains:

• Why passengers fall sideways when a bus turns
• Why seat belts are necessary

👉 Key Point: Inertia depends on mass (more mass = more inertia)

✅ Newton’s Second Law

Force acting on an object is equal to mass × acceleration. F=ma.

👉 This explains:

• If force increases → acceleration increases
• If mass increases → acceleration decreases

👉 Example:

• A lighter object accelerates faster than a heavier one under same force

✅ Newton’s Third Law

For every action, there is an equal and opposite reaction.

👉 This explains:

• Swimming (pushing water backward)
• Rocket motion
• Walking

2. Momentum and Its Conservation

Momentum is the product of mass and velocity. P=mv

👉 Important Points:

• Depends on mass and velocity
• A fast truck has more momentum than a bicycle

✅ Law of Conservation of Momentum

In an isolated system, total momentum remains constant.

👉 Frequently asked in TNPSC exams

3. Impulse and Change in Momentum

Impulse is the change in momentum.

👉 Formula:
Impulse = Force × Time

👉 Key Understanding:

• Increasing time reduces force (seat belts increase stopping time → reduce injury)

4. Force and Types of Forces

✅ Force is:

A push or pull that can change motion

Types:

• Contact force → friction, normal force
• Non-contact force → gravitational, magnetic

5. Friction and Motion

Friction opposes motion and depends on surface nature.

👉 Important Applications:

• Roads are curved to provide better grip
• Stopping distance increases when friction is low (wet roads)

Practical Applications (VERY IMPORTANT FOR TNPSC)

• Seat belts → First law (inertia)
• Running before long jump → increases momentum
• Balloon release → action-reaction (air escapes backward, balloon moves forward)
• Curved roads → friction + centripetal force

Final Revision Tips 🚀

• Remember all 3 Newton laws with examples
• Focus on F = ma and p = mv numericals
• Understand real-life applications (very important for TNPSC)
• Revise momentum & impulse concepts carefully

Most Expected TNPSC Questions from Laws of Motion

• Questions based on Newton’s Laws (direct concept)
• Numerical problems using F = ma
• Momentum comparison questions
• Real-life application (seat belt, walking, swimming)
• Impulse and change in momentum

For more detailed explanation, refer:
🔗 NCERT Class 11 Physics – Laws of Motion