Introduction to Physics

• Physics is a natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force.
• Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

Core Concepts

• Physics covers a wide range of phenomena, from subatomic particles to galaxies.
• Classical physics, developed before the 20th century, includes mechanics, thermodynamics, optics, and electromagnetism.
• Modern physics includes relativity and quantum mechanics.

Mechanics

• Mechanics deals with the motion of bodies under the influence of forces.
• Kinematics describes motion without considering the causes, focusing on displacement, velocity, and acceleration.
• Dynamics relates motion to its causes, especially forces and torques, using Newton's laws of motion.
• Newton's first law states that an object remains at rest or in uniform motion unless acted upon by a force.
• Newton's second law states that the force acting on an object is equal to the mass of that object times its acceleration (F = ma).
• Newton's third law states that for every action, there is an equal and opposite reaction.
• Conservation laws, such as the conservation of energy, momentum, and angular momentum, are fundamental principles in mechanics.

Thermodynamics

• Thermodynamics deals with heat, work, and energy, and the relationships between them.
• The zeroth law of thermodynamics states that if two systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.
• The first law of thermodynamics states that energy is conserved: the change in internal energy of a system is equal to the heat added to the system minus the work done by the system.
• The second law of thermodynamics states that the total entropy of an isolated system can only increase over time.
• The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero.
• Thermodynamic processes include isothermal (constant temperature), adiabatic (no heat exchange), isobaric (constant pressure), and isochoric (constant volume) processes.

Electromagnetism

• Electromagnetism is the study of the electromagnetic force, which is one of the four fundamental forces of nature.
• Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electromagnetic field.
• Coulomb's law describes the force between electric charges.
• Electric fields are created by electric charges and exert forces on other charges.
• Magnetic fields are created by moving electric charges (electric current) and exert forces on other moving charges.
• Faraday's law of induction states that a changing magnetic field creates an electric field.
• Maxwell's equations describe the behavior of electric and magnetic fields and their interaction with matter.
• Electromagnetic waves, such as light, are disturbances in electric and magnetic fields that propagate through space.

Optics

• Optics is the study of light and its behavior.
• Reflection occurs when light bounces off a surface.
• Refraction occurs when light bends as it passes from one medium to another.
• Lenses use refraction to focus or disperse light.
• Wave optics deals with phenomena such as interference and diffraction, which demonstrate the wave nature of light.
• The Doppler effect describes the change in frequency of a wave due to the motion of the source or observer.

Relativity

• Relativity, developed by Albert Einstein, consists of two main theories: special relativity and general relativity.
• Special relativity deals with the relationship between space and time for objects moving at constant velocity.
• It postulates that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source.
• Mass-energy equivalence is expressed by the equation E=mc², where E is energy, m is mass, and c is the speed of light.
• General relativity deals with gravity as a curvature of spacetime caused by mass and energy.
• General relativity predicts phenomena such as gravitational lensing and gravitational waves.

Quantum Mechanics

• Quantum mechanics deals with the behavior of matter and energy at the atomic and subatomic levels.
• Quantization means that certain physical quantities, such as energy and angular momentum, can only take on discrete values.
• Wave-particle duality means that particles can exhibit wave-like properties and waves can exhibit particle-like properties.
• The Heisenberg uncertainty principle states that it is impossible to know both the position and momentum of a particle with perfect accuracy.
• Quantum entanglement is a phenomenon in which particles become correlated such that the state of one particle instantaneously affects the state of the other, regardless of the distance between them.
• The Schrödinger equation describes the evolution of quantum systems over time.

Units and Measurement

• The International System of Units (SI) is the standard system of units used in physics.
• The base units in the SI system are the meter (m) for length, the kilogram (kg) for mass, the second (s) for time, the ampere (A) for electric current, the kelvin (K) for temperature, the mole (mol) for amount of substance, and the candela (cd) for luminous intensity.
• Derived units are combinations of base units, such as the newton (N) for force (kg⋅m/s²) and the joule (J) for energy (kg⋅m²/s²).
• Scientific notation is used to express very large or very small numbers in a concise form.
• Error analysis is used to quantify the uncertainty in measurements.

Mathematical Tools

• Calculus is used to describe rates of change and accumulation, and is essential for solving many problems in physics.
• Vectors are used to represent quantities that have both magnitude and direction, such as velocity, force, and electric field.
• Linear algebra is used to solve systems of linear equations and to represent transformations in space.
• Differential equations are used to describe the evolution of physical systems over time.
• Probability and statistics are used to analyze random phenomena and to estimate the uncertainty in measurements.