Introduction to Physics: Core Concepts and Mechanics

• Physics is the natural science focused on matter, its fundamental parts, motion, behavior through space and time, and energy and force.

Core Concepts

• Physics spans phenomena from subatomic particles to entire galaxies.
• Physics aims to create comprehensive laws governing the universe.
• Classical physics includes mechanics, thermodynamics, optics, and electromagnetism.
• Modern physics includes quantum mechanics and relativity.

Mechanics

• Mechanics studies the motion of objects and the forces causing this motion.
• Kinematics describes motion, irrespective of its causes.
• Dynamics studies the connection between motion and its causes, namely forces.
• Newton's laws of motion are key to classical mechanics.
  • First Law: Objects remain at rest or in uniform motion unless a force acts upon them.
  • Second Law: Force equals the rate of change of momentum; for constant mass, Force = mass x acceleration (F = ma).
  • Third Law: Every action has an equal and opposite reaction.

Thermodynamics

• Thermodynamics studies heat, work, energy, and their interrelations.
• The laws of thermodynamics are foundational.
  • Zeroth Law: Systems in thermal equilibrium with a third system are in equilibrium with each other.
  • First Law: Energy is conserved; it can only be transferred or converted.
  • Second Law: The entropy of an isolated system increases over time.
  • Third Law: Entropy approaches a minimum or zero as temperature approaches absolute zero.
• Heat transfers through conduction, convection, and radiation.

Electromagnetism

• Electromagnetism studies the interaction of electric and magnetic fields.
• Electric charge is a fundamental property.
• Coulomb's Law details the force between electric charges.
• Moving electric charges produce magnetic fields.
• Faraday's Law of Induction explains how changing magnetic fields create electric fields.
• Maxwell's equations connect electricity and magnetism and predict electromagnetic waves (light).

Optics

• Optics studies light and its behavior.
• Reflection is light bouncing off surfaces.
• Refraction is light bending as it passes between media.
• Diffraction is the spreading of waves passing openings or obstacles.
• Interference is the combination of waves, producing constructive or destructive patterns.
• Lenses and mirrors focus or redirect light.

Quantum Mechanics

• Quantum mechanics studies matter at atomic/subatomic levels.
• Energy is quantized, existing in discrete amounts (quanta).
• The Heisenberg Uncertainty Principle states that position and momentum cannot both be perfectly known.
• Wave-particle duality: Particles act like waves, and waves act like particles.
• Schrödinger's equation portrays how quantum mechanical systems evolve over time.

Relativity

• Relativity, by Albert Einstein, includes special and general relativity.
• Special relativity relates space and time for observers at constant velocities.
  • The speed of light is constant for all observers.
  • Time dilation: Time slows for moving objects relative to stationary ones.
  • Length contraction: Moving object lengths shorten in the direction of motion relative to stationary observers.
  • Mass increases with velocity.
  • Mass-energy equivalence: E = mc², where E is energy, m is mass, and c is the speed of light.
• General relativity describes gravity as the curvature of spacetime by mass and energy.
  • Gravity results from spacetime curvature, not a force.
  • General relativity predicts gravitational lensing and gravitational waves.

Units and Measurement

• The International System of Units (SI) is the standard in physics.
• Base SI units:
  • Meter (m) for length.
  • Kilogram (kg) for mass.
  • Second (s) for time.
  • Ampere (A) for electric current.
  • Kelvin (K) for temperature.
  • Mole (mol) for the amount of substance.
  • Candela (cd) for luminous intensity.
• Derived units combine base units, for example, Newton (N) for force and Joule (J) for energy.
• Scientific notation expresses very large/small numbers.
• Uncertainty exists in all measurements.

Problem Solving

• Find the knowns and unknowns.
• Select relevant equations and principles.
• Solve equations algebraically before inserting numbers.
• Check the units.
• Assess if the answer is reasonable.

Overview of physics as a natural science, covering matter, motion, energy, and force. Includes classical mechanics, kinematics, dynamics, and Newton's laws of motion. Covers the main goal of physics and its comprehensive laws.