# Physics Knowledge Base

## Classical Mechanics
### Newton's Laws
- **First Law**: An object remains at rest or in uniform motion unless acted upon by a net force
- **Second Law**: F = ma (Force equals mass times acceleration)
- **Third Law**: For every action, there is an equal and opposite reaction

### Kinematics
- **Displacement**: Change in position of an object
- **Velocity**: Rate of change of displacement (vector quantity)
- **Acceleration**: Rate of change of velocity
- **Equations of Motion**: v = u + at, s = ut + ½at², v² = u² + 2as

### Dynamics
- **Force**: Push or pull that can change motion
- **Weight**: Gravitational force on an object (W = mg)
- **Friction**: Force opposing relative motion
- **Tension**: Force transmitted through strings or cables

## Energy and Work
### Forms of Energy
- **Kinetic Energy**: Energy of motion (KE = ½mv²)
- **Potential Energy**: Stored energy due to position
- **Gravitational PE**: PE = mgh (mass × gravity × height)
- **Elastic PE**: Energy stored in deformed objects

### Work and Power
- **Work**: Force × displacement in direction of force
- **Power**: Rate of doing work (P = W/t)
- **Efficiency**: Useful work output / total work input
- **Conservation of Energy**: Energy cannot be created or destroyed

## Thermodynamics
### Laws of Thermodynamics
- **Zeroth Law**: If two systems are in thermal equilibrium with a third, they are in equilibrium with each other
- **First Law**: Energy cannot be created or destroyed (ΔU = Q - W)
- **Second Law**: Entropy of an isolated system always increases
- **Third Law**: Entropy approaches zero as temperature approaches absolute zero

### Heat and Temperature
- **Temperature**: Measure of average kinetic energy
- **Heat**: Energy transferred due to temperature difference
- **Specific Heat**: Energy required to raise 1kg by 1°C
- **Latent Heat**: Energy for phase changes without temperature change

## Waves and Oscillations
### Wave Properties
- **Amplitude**: Maximum displacement from equilibrium
- **Wavelength**: Distance between consecutive peaks
- **Frequency**: Number of oscillations per second
- **Period**: Time for one complete oscillation

### Types of Waves
- **Transverse Waves**: Oscillations perpendicular to wave direction
- **Longitudinal Waves**: Oscillations parallel to wave direction
- **Standing Waves**: Waves that appear to stand still
- **Resonance**: Amplitude increase at natural frequency

## Electricity and Magnetism
### Electric Charges
- **Coulomb's Law**: F = k(q₁q₂)/r²
- **Electric Field**: Force per unit charge
- **Electric Potential**: Work per unit charge
- **Capacitance**: Charge storage ability

### Electric Current
- **Ohm's Law**: V = IR (Voltage = Current × Resistance)
- **Power**: P = VI = I²R = V²/R
- **Series Circuits**: Current same, voltage adds
- **Parallel Circuits**: Voltage same, current adds

### Magnetism
- **Magnetic Field**: Region where magnetic forces act
- **Lorentz Force**: F = q(E + v×B)
- **Faraday's Law**: Induced EMF proportional to rate of flux change
- **Lenz's Law**: Induced current opposes flux change

## Modern Physics
### Quantum Mechanics
- **Wave-Particle Duality**: Matter exhibits both wave and particle properties
- **Heisenberg Uncertainty**: Cannot simultaneously know position and momentum exactly
- **Quantum Tunneling**: Particles can pass through energy barriers
- **Superposition**: Quantum systems can exist in multiple states simultaneously

### Relativity
- **Special Relativity**: E = mc², time dilation, length contraction
- **General Relativity**: Gravity as curvature of spacetime
- **Mass-Energy Equivalence**: Mass and energy are interchangeable
- **Spacetime**: Four-dimensional fabric of universe

## Optics
### Light Properties
- **Reflection**: Light bouncing off surfaces
- **Refraction**: Light bending when changing medium
- **Diffraction**: Light bending around obstacles
- **Interference**: Light waves combining constructively or destructively

### Lenses and Mirrors
- **Convex Lens**: Converges light rays
- **Concave Lens**: Diverges light rays
- **Focal Length**: Distance from lens to focal point
- **Magnification**: Ratio of image to object size