Mechanics occupies more than 40% of Class 11 Physics and is the conceptual foundation for Class 12. Getting Mechanics right in Class 11 pays dividends for two full years.
Mechanics Chapters and Marks
| Chapter | Marks | Difficulty |
|---|---|---|
| Kinematics | 8 | Medium |
| Laws of Motion | 8 | Hard |
| Work, Energy and Power | 6 | Medium |
| Rotational Motion | 8 | Hard |
| Gravitation | 6 | Medium |
Kinematics: The Non-Negotiables
- Equations of motion — derive all 3 using calculus method
- Projectile motion — split into horizontal (constant velocity) and vertical (free fall) components
- Relative velocity — subtraction of velocity vectors with direction
Laws of Motion: Where Most Marks Are Lost
- Always draw Free Body Diagram before writing any equation
- Friction types: static (fs max = us x N), kinetic (fk = uk x N)
- Circular motion: centripetal acceleration a = v2/r, force F = mv2/r directed inward
- Newton 3rd law: action and reaction act on DIFFERENT objects
Rotational Motion: The Hardest Chapter
- Moment of inertia — standard results: rod, disk, sphere, cylinder about different axes
- Parallel axis theorem and perpendicular axis theorem
- Conservation of angular momentum: L = Iw = constant when no external torque
- Rolling without slipping: KE = (1/2)mv2 + (1/2)Iw2
Tip
Rotational Motion is the chapter where Class 11 students score 0 or full marks. Spend 2 full weeks on this chapter alone. Work through every NCERT example before attempting reference books.