+2 Physics Mechanics and Energy Concepts

+2 ka Physics (Class 12 Physics)

1. Mechanics

• Kinematics: Study of motion without considering forces.
  • Equations of motion for uniform acceleration:
    • v = u + at
    • s = ut + (1/2)at²
    • v² = u² + 2as
• Newton's Laws of Motion:
  • First Law: Object remains in rest or uniform motion unless acted upon by a force.
  • Second Law: F = ma (Force equals mass times acceleration).
  • Third Law: For every action, there is an equal and opposite reaction.

2. Work, Energy, and Power

• Work (W): W = Fd cos(θ), where θ is the angle between force and displacement.
• Kinetic Energy (KE): KE = (1/2)mv².
• Potential Energy (PE): PE = mgh.
• Conservation of Energy: Total energy remains constant in an isolated system.

3. System of Particles and Rotational Motion

• Centre of Mass: The point where the mass of a system is concentrated.
• Torque (τ): τ = rF sin(θ); τ causes rotational motion.
• Angular momentum (L): L = Iω (I is the moment of inertia, ω is the angular velocity).

4. Gravitation

• Law of Universal Gravitation: F = G(m₁m₂)/r², where G is the gravitational constant.
• Gravitational Potential Energy: U = -G(m₁m₂)/r.
• Orbital Motion: Satellite motion governed by gravitational force.

5. Mechanical Properties of Solids and Fluids

• Elasticity: Measure of how much a material can deform under stress.
• Pressure (P): P = F/A; also relates to fluid statics (P = ρgh).
• Viscosity: Resistance to flow in fluids; Poiseuille's law describes flow in pipes.

6. Thermodynamics

• Laws of Thermodynamics:
  • First Law: ΔU = Q - W (Change in internal energy).
  • Second Law: Entropy of an isolated system never decreases.
• Heat Engines and Refrigerators: Efficiency concepts, Carnot engine.

7. Waves and Oscillations

• Simple Harmonic Motion (SHM): Motion in which restoring force is proportional to displacement.
• Wave Properties:
  • Types: Transverse and longitudinal waves.
  • Speed of wave: v = fλ (frequency times wavelength).

8. Optics

• Reflection and Refraction:
  • Laws of reflection: Angle of incidence equals angle of reflection.
  • Snell's Law: n₁ sin(θ₁) = n₂ sin(θ₂).
• Lenses and Mirrors:
  • Lens formula: 1/f = 1/v - 1/u.
  • Magnification: m = h'/h = -v/u.

9. Electromagnetism

• Coulomb’s Law: F = k(q₁q₂)/r²; describes force between charges.
• Electric Current (I): I = Q/t.
• Magnetic Fields: Magnetic force on a charge moving in a field; F = qvB sin(θ).

10. Modern Physics

• Photoelectric Effect: Emission of electrons when light shines on a material.
• Atomic Models: Rutherford's model, Bohr's model of the hydrogen atom.
• Nuclear Physics: Concepts of radioactivity, fission, and fusion.

11. Practical Skills

• Lab Experiments: Understanding practical applications and experiments related to all topics.
• Graphical Analysis: Skills in interpreting and drawing graphs related to motion, forces, and energy.

These notes summarize the fundamental concepts covered in Class 12 Physics, providing a concise overview for study and review.