NDA & CDS 2 2025 Exam Physics Revision Class 2

Introduction

Physics is the foundation of understanding natural phenomena, and for aspirants of the NDA (National Defence Academy) and CDS (Combined Defence Services) examinations, mastering its concepts is essential. Among the most important topics in the Physics syllabus are Waves and Laws of Motion. These chapters not only build the core understanding of mechanics but also serve as a base for solving complex problems in real-life applications, including defense technology, navigation, and communication systems. A systematic revision of these topics ensures clarity and precision, which are crucial for scoring well in the exam.

Waves

A wave is a disturbance that travels through a medium or space, transferring energy without the transfer of matter. Waves are broadly classified into:

1. Mechanical Waves – Require a medium for propagation. Examples: Sound waves, water waves.
   • Longitudinal Waves: Particles oscillate parallel to wave propagation (e.g., sound waves).
   • Transverse Waves: Particles oscillate perpendicular to wave propagation (e.g., waves on a string).
2. Electromagnetic Waves – Do not require a medium and can travel through vacuum (e.g., light, radio waves).

Key concepts for revision:

• Wave speed, frequency, wavelength, and their interrelationship (v = fλ).
• Principle of Superposition and Interference.
• Resonance and Standing Waves.
• Doppler Effect and its applications in defense and astronomy.

Understanding waves is vital, as the principles are applied in radar, sonar, wireless communication, and signal transmission, all of which play crucial roles in defense services.

Laws of Motion

Sir Isaac Newton’s Laws of Motion form the backbone of classical mechanics. They describe the relationship between forces and motion, helping us understand how objects behave under various conditions.

1. First Law (Law of Inertia): An object continues in its state of rest or uniform motion unless acted upon by an external force.
2. Second Law: The rate of change of momentum of an object is directly proportional to the force applied (F = ma).
3. Third Law: For every action, there is an equal and opposite reaction.

Key points to revise:

• Applications of Newton’s Laws in daily life and defense scenarios.
• Motion on an inclined plane, frictional forces, and equilibrium of bodies.
• Circular motion and centripetal force.
• Impulse and momentum in collisions.

These principles are not just theoretical; they are applied in ballistics, flight dynamics, naval engineering, and space missions, areas where precision and understanding of motion are indispensable.

Conclusion

The topics of Waves and Laws of Motion hold immense significance in both the NDA/CDS examinations and in practical defense applications. A clear grasp of these concepts empowers candidates to solve numerical problems with confidence and to appreciate the scientific principles underlying modern defense technology. By mastering the fundamentals and practicing a variety of problems, aspirants can strengthen their preparation and move one step closer to success in NDA CDS 2 (2025).