What are the basics of physics?

1. **Classical Mechanics**:

- **Kinematics**: Describes the motion of objects without considering the causes. Key concepts include displacement, velocity, acceleration, and time.

- **Dynamics**: Focuses on the forces and their effects on motion. Newton's laws of motion are central:

- **First Law (Inertia)**: An object remains at rest or in uniform motion unless acted upon by a force.

- **Second Law**: The force acting on an object is equal to its mass times its acceleration (F = ma).

- **Third Law**: For every action, there is an equal and opposite reaction.

- **Energy**: Concepts of kinetic energy (energy of motion) and potential energy (stored energy).

- **Momentum**: Product of an object's mass and velocity, conserved in isolated systems.

2. **Thermodynamics**:

- **Temperature and Heat**: Temperature is a measure of the average kinetic energy of particles. Heat is energy transferred due to temperature difference.

- **Laws of Thermodynamics**:

- **First Law**: Energy cannot be created or destroyed, only transformed (conservation of energy).

- **Second Law**: Entropy of an isolated system always increases; heat flows from hot to cold.

- **Third Law**: As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

3. **Electromagnetism**:

- **Electricity**: Study of electric charges, electric fields, and electric potentials. Ohm's law (V = IR) relates voltage, current, and resistance.

- **Magnetism**: Study of magnetic fields and forces. Electromagnetic induction explains how changing magnetic fields produce electric currents (Faraday's law).

- **Maxwell's Equations**: Describe how electric and magnetic fields are generated and altered by each other and by charges and currents.

4. **Optics**:

- **Light**: Described as both a wave and a particle (wave-particle duality).

- **Reflection and Refraction**: Behavior of light as it interacts with surfaces and materials.

- **Lenses and Mirrors**: Principles of image formation and focal points.

5. **Modern Physics**:

- **Relativity**: Introduced by Einstein. Special relativity deals with objects moving at constant speeds close to the speed of light, showing that time and space are relative. General relativity describes gravity as the curvature of spacetime.

- **Quantum Mechanics**: Study of particles at the atomic and subatomic levels. Key principles include wave-particle duality, quantization of energy, and the uncertainty principle (Heisenberg's uncertainty principle).

6. **Atomic and Nuclear Physics**:

- **Atoms**: Consist of a nucleus (protons and neutrons) and electrons. Quantum mechanics explains the behavior of electrons in atoms.

- **Radioactivity**: Decay of unstable atomic nuclei, emitting radiation (alpha, beta, and gamma rays).

- **Nuclear Reactions**: Fusion (combining nuclei) and fission (splitting nuclei), with applications in energy production.

These principles and concepts form the foundation of physics, helping us understand the natural world and the laws that govern it.