Intro to Physics: Core Concepts

• Physics is a natural science examining matter and its basic parts, motion and behavior across space and time, and related concepts like energy and force.
• A core scientific field, physics seeks to define the behavior of the universe.
• The scientific method is employed in physics to create and assess hypotheses derived from experimental observations.
• The goal of physics is to create theories that can accurately describe the physical world and make predictions about future occurrences.

Core Concepts

• Classical mechanics explains the movement of macroscopic objects, including projectiles, machine components, and astronomical objects.
• Thermodynamics studies heat, work, and energy, including how they relate to one another.
• Electromagnetism studies the forces that exist between electrically charged particles.
• Optics examines the characteristics and behavior of light, including how it interacts with matter, and creates instruments for using or detecting light.
• Quantum mechanics studies how matter behaves at the atomic and subatomic levels.
• Relativity studies gravity, the structure of spacetime, and the behavior of fast-moving objects.

Branches of Physics

• Classical Mechanics: The movement of objects in response to forces is studied.
• Thermodynamics: Studies the relationships between heat, temperature, energy, and work.
• Electromagnetism: Studies how magnetic fields and electric currents or fields interact.
• Optics: Light and its behavior are studied.
• Acoustics: Studies sound and mechanical waves.
• Quantum Mechanics: Studies the behavior of matter and energy at the atomic and subatomic levels.
• Nuclear Physics: Studies the behavior, interactions, structure, and components of atomic nuclei.
• Particle Physics: The study of matter's fundamental building blocks, radiation, and how they interact.
• Condensed Matter Physics: Concentrates on the physical characteristics of matter in condensed states.
• Astrophysics: Uses physics to explain astronomical objects and events.

Key Quantities and Units

• Length is measured in meters (m).
• Mass is measured in kilograms (kg).
• Time is measured in seconds (s).
• Electric Current is measured in amperes (A).
• Temperature is measured in kelvins (K).
• Amount of Substance is measured in moles (mol).
• Luminous Intensity is measured in candelas (cd).
• Force is measured in newtons (N).
• Energy is measured in joules (J).
• Power is measured in watts (W).

Classical Mechanics

• Kinematics describes the motion of objects without considering the forces that cause the motion.
• Dynamics describes the motion of objects considering the forces that cause the motion.
• Newton's Laws of Motion:
  • An object at rest remains at rest, and an object in motion remains in motion with the same speed and direction unless a force acts upon it (First Law).
  • The acceleration of an object is directly proportional to the net force acting on it, is in the same direction as the net force, and is inversely proportional to the mass of the object (F = ma) (Second Law).
  • For every action, there is an equal and opposite reaction (Third Law).
• Work is the energy transferred to or from an object by means of a force acting on the object.
• Energy is the capacity to do work.
  • Kinetic energy is the energy of motion.
  • Potential energy is the energy stored in an object due to its position or configuration.
• Conservation of Energy: The total energy of an isolated system remains constant.
• Momentum is the product of the mass of an object and its velocity.
• Conservation of Momentum: In a closed system, the total momentum remains constant.
• Angular momentum measures how much an object rotates, taking into account its mass, shape, and speed.
• Torque is a twisting force that tends to cause rotation.
• Gravitation is the attractive force between objects with mass.

Thermodynamics

• Thermodynamics studies the relationships between heat, work, and energy.
• Temperature is a measurement of the average kinetic energy of a system's particles.
• Heat is the transfer of thermal energy caused by a temperature difference between objects or systems.
• Zeroth Law of Thermodynamics: Two systems in thermal equilibrium with a third system are in thermal equilibrium with each other.
• First Law of Thermodynamics: A system's change in internal energy equals the heat added to the system less the work performed by the system.
• Second Law of Thermodynamics: The total entropy of an isolated system can only increase over time.
• Entropy measures a system's disorder or randomness.
• Heat Engines convert thermal energy into mechanical work.
• Refrigerators transfer thermal energy from a cold reservoir to a hot reservoir.

Electromagnetism

• Electromagnetism studies how magnetic fields and electric charges interact.
• Electric Charge: A fundamental property of matter that causes it to experience a force when placed in an electromagnetic field.
• Electric Field: A region of space around an electrically charged object in which a force would be exerted on other charged objects.
• Electric Force: The force between electrically charged objects.
• Coulomb's Law: The electric force between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.
• Electric Potential: The electric potential energy per unit charge at a specific location.
• Current: The rate of flow of electric charge.
• Resistance: A measure of the opposition to the flow of electric current.
• Ohm's Law: The voltage across a conductor is directly proportional to the current flowing through it (V = IR).
• Capacitance: The ability of a system to store electric charge.
• Magnetic Field: A region of space around a magnet or electric current in which a force would be exerted on other magnets or moving charges.
• Magnetic Force: The force between magnets or moving charges.
• Faraday's Law of Induction: A changing magnetic field induces an electromotive force (EMF) in a circuit.
• Inductance: The property of a circuit by which a change in current induces an EMF in the same circuit or in a nearby circuit.
• Electromagnetic Waves: Disturbances in electric and magnetic fields that propagate through space, including radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

Optics

• Optics studies light's behavior and characteristics.
• Reflection: The bouncing of light off a surface.
• Refraction: The bending of light as it passes from one medium to another.
• Lenses: Devices that refract light to form an image.
• Interference: The superposition of two or more waves, resulting in either constructive or destructive interference.
• Diffraction: The bending of waves around obstacles or through openings.
• Polarization: The alignment of the electric field vectors of light waves in a particular direction.

Quantum Mechanics

• Quantum Mechanics examines how matter behaves at the atomic and subatomic levels.
• Quantization: Certain physical quantities, like energy and angular momentum, can only have discrete values.
• Wave-Particle Duality: Particles can behave as both waves and particles.
• Heisenberg Uncertainty Principle: The exact position and momentum of a particle cannot be known simultaneously.
• Schrödinger Equation: A mathematical equation that describes the evolution of the quantum state of a system.
• Quantum Entanglement: Two or more objects' quantum states are related even when separated by a considerable distance in this quantum mechanical phenomena.

Relativity

• The structure of spacetime and gravity are examined in relativity.
• Special Relativity:
  • The laws of physics are the same for all observers in uniform motion.
  • The speed of light in a vacuum is the same for all observers, regardless of the motion of the light source.
  • Time dilation: Time passes more slowly for moving observers relative to stationary observers.
  • Length contraction: The length of an object moving at a high speed appears to be shorter in the direction of motion than its length when at rest.
  • Mass-energy equivalence: Energy and mass are interchangeable (E=mc^2).
• General Relativity:
  • Gravity is not a force, but rather a curvature of spacetime caused by the presence of mass and energy.
  • Gravitational lensing: The bending of light around massive objects.
  • Black holes: Regions of spacetime where gravity is so strong that nothing, not even light, can escape.