Physics: fundamental concepts

• Physics delves into matter, its basic parts, motion through space-time, and related concepts like energy and force.
• It aims to grasp the behavior of the universe.
• It explores interactions between energy, matter, space, and time.
• Physicists investigate phenomena from subatomic particles to galaxies.
• Physics is quantitative and uses mathematics.

Core Concepts

• Classical mechanics studies motion of macroscopic objects influenced by forces.
• Thermodynamics studies energy transfer/transformation, particularly heat, relative to temperature, volume, and pressure.
• Electromagnetism studies electric currents and magnetic fields, linking electricity, magnetism, and light as aspects of the same force.
• Quantum mechanics studies matter/energy behavior at atomic/subatomic levels.
• Relativity (special and general) studies spacetime structure and gravity's effects.

Mechanics

• Kinematics describes motion without considering causes, involving displacement, velocity, and acceleration.
• Dynamics studies forces and their effects on motion using Newton's laws.
• Newton's First Law (Inertia): Objects at rest stay at rest; objects in motion stay in motion unless a force acts.
• Newton's Second Law: Force equals mass times acceleration (F = ma).
• Newton's Third Law: Every action has an equal, opposite reaction.
• Work is energy transferred by a force causing displacement.
• Energy enables work.
• Kinetic energy is energy of motion.
• Potential energy is energy of position/condition.
• Energy conservation: Total energy in an isolated system remains constant.

Thermodynamics

• Temperature measures average kinetic energy of particles in a substance.
• Heat is thermal energy transfer due to temperature differences.
• The first law of thermodynamics states that energy is conserved; the change in internal energy of a system equals heat added minus work done (ΔU = Q - W).
• Entropy measures a system's disorder or randomness.
• The second law of thermodynamics states that total entropy in an isolated system increases over time.
• Heat transfers via conduction, convection, and radiation.
• Conduction transfers heat through a material without material motion.
• Convection transfers heat through fluid movement.
• Radiation transfers heat through electromagnetic waves.

Electromagnetism

• Electric charge causes matter to experience force in an electromagnetic field.
• Coulomb's law gives the force between charges: F = k * (q1 * q2) / r^2.
• Electric field is the force per unit charge on a test charge.
• Electric potential (voltage) is electric potential energy per unit charge.
• Electric current is the rate of electric charge flow.
• Resistance opposes electric current flow.
• Ohm's Law: V = IR (voltage = current x resistance).
• Magnetism is a force from moving electric charges.
• Magnetic fields are created by moving charges and magnetic materials.
• Electromagnetic induction generates voltage across a conductor in a changing magnetic field.
• Maxwell's equations describe electric and magnetic field behavior/interactions.

Waves and Optics

• A wave is a disturbance transferring energy through a medium/space.
• Waves are transverse (e.g., light) or longitudinal (e.g., sound).
• Wavelength is the distance between wave crests or troughs.
• Frequency is the number of wave cycles per unit time.
• Amplitude is the maximum wave displacement.
• Wave speed: v = fλ (frequency x wavelength).
• Interference occurs when waves overlap, creating constructive (increased amplitude) or destructive (decreased amplitude) effects.
• Diffraction is the bending of waves around obstacles/openings.
• Refraction is the bending of waves passing between mediums.
• Optics studies light's behavior and properties.
• Reflection is light bouncing off a surface.
• Lenses refract light to form images.

Quantum Mechanics

• Quantum mechanics describes behavior of matter and energy at the atomic and subatomic level.
• Quantization: Energy, momentum, and other physical quantities take on discrete values.
• Wave-particle duality: Particles act as waves, and waves act as particles.
• Heisenberg's Uncertainty Principle: It is impossible to know a particle's exact position and momentum simultaneously.
• Quantum entanglement: Particles become correlated, so one particle's state affects the other instantly, regardless of distance.
• Quantum tunneling: A particle passes through a potential energy barrier even without enough energy to overcome it classically.

Relativity

• Special relativity relates space and time for observers in uniform motion.
• The speed of light is constant for all observers.
• Time dilation is the slowing of time for a moving object.
• Length contraction is the shortening of an object in motion direction as its speed nears light speed.
• Mass-energy equivalence: E = mc^2.
• General relativity describes gravity as spacetime curvature caused by mass/energy.
• Gravitational time dilation: Time slows in stronger gravitational fields.
• Black holes are regions with gravity so strong that nothing can escape, not even light.

Nuclear Physics

• Nuclear physics studies atomic nuclei structure, properties, and reactions.
• The atomic nucleus contains protons and neutrons.
• Isotopes are atoms of the same element with different neutron numbers.
• Radioactive decay is when unstable nuclei emit particles/energy to become stable.
• Types of radioactive decay: alpha, beta, and gamma decay.
• Nuclear fission splits a heavy nucleus into lighter ones, releasing energy.
• Nuclear fusion combines light nuclei into a heavier one, releasing energy.
• Nuclear reactions involve changes in the nuclei of atoms.

Standard Model

• The Standard Model describes fundamental particles and forces.
• Fundamental particles: quarks, leptons, and bosons.
• Quarks form protons and neutrons.
• Leptons include electrons and neutrinos.
• Bosons carry forces.
• Four fundamental forces: strong, weak, electromagnetic, and gravitational.
• The strong force holds nuclei together.
• The weak force causes radioactive decay.
• The electromagnetic force acts between charged particles.
• The gravitational force acts between objects with mass.

Measurement and Units

• Physics depends on quantitative measurements.
• The International System of Units (SI) is the physics standard.
• SI base units: meter (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for current, kelvin (K) for temperature, mole (mol) for substance amount, candela (cd) for luminous intensity.
• Derived units combine base units (e.g., newton (N) for force, kg*m/s^2).
• Scientific notation expresses very large/small numbers.

Problem Solving

• Systematic problem-solving is essential.
• Identify knowns and unknowns.
• Choose relevant equations/principles.
• Solve equations algebraically.
• Substitute values and calculate.
• Check units and answer significance.