Introduction to Physics

• Physics is a natural science examining matter, fundamental constituents, motion and behavior through space and time, and related entities of energy and force
• Physics is one of the most fundamental scientific disciplines
• The main goal of physics is understanding how the universe behaves

Core Concepts

• Mechanics deals with the motion of objects and the forces causing it
• Thermodynamics addresses heat, work, energy, and the relationships between them
• Electromagnetism concerns forces between electrically charged particles
• Optics studies light and its behavior
• Quantum mechanics studies the behavior of matter and energy at atomic and subatomic levels

Mechanics

• Kinematics describes object motion without considering causative forces
  • Displacement is the change in an object's position
  • Velocity is the rate of change of displacement
  • Acceleration is the rate of change of velocity
• Dynamics deals with forces affecting object motion
  • Force is an interaction that, if unopposed, changes an object's motion
  • Newton's Laws of Motion:
    • First Law: Objects at rest stay at rest, and objects in motion stay in motion with the same speed and direction unless acted upon by a force
    • Second Law: Force equals the change in momentum per change in time; for constant mass, force equals mass times acceleration (F = ma)
    • Third Law: Every action has an equal and opposite reaction.
  • Momentum is the product of mass and velocity
  • Energy is the ability to do work
    • Kinetic Energy is the energy of motion
    • Potential Energy is the energy of position

Thermodynamics

• Temperature measures the average kinetic energy of particles in a system
• Heat is energy transfer between objects/systems due to temperature differences
• Laws of Thermodynamics:
  • Zeroth Law: If two systems are in thermal equilibrium with a third, they're in equilibrium with each other
  • First Law: Energy is conserved; the change in a system's internal energy equals heat added minus work done
  • Second Law: Entropy in an isolated system increases or remains constant; spontaneous processes increase the total entropy of the universe
  • Third Law: As temperature approaches absolute zero, entropy approaches a minimum/zero
• Entropy measures the disorder or randomness of a system

Electromagnetism

• Electric Charge: A physical property of matter causing it to experience force in an electromagnetic field
  • Coulomb's Law: Describes force between two electric charges; proportional to the product of charges, inversely proportional to the square of the distance between them
• Electric Field: The region around an electric charge where another charge experiences a force
• Electric Potential: Electric potential energy per unit charge at a specific location
• Magnetism: A force exerted by moving electric charges
  • Magnetic Field: A region around a magnet/moving charge where another magnet/moving charge experiences force
• Electromagnetic Induction: Production of an electromotive force (EMF) across a conductor in a changing magnetic field
• Maxwell's Equations: Four equations describing the behavior and interactions of electric and magnetic fields

Optics

• Reflection: The change in direction of a wavefront at an interface between two media, returning into the originating medium
• Refraction: Bending of a wave when passing from one medium to another
• Lenses: Devices that refract light to focus or disperse it
• Diffraction: Bending of waves around obstacles or through openings
• Interference: Superposition of waves, resulting in constructive or destructive patterns

Quantum Mechanics

• Quantum: The minimum amount of any physical property in an interaction
• Wave-Particle Duality: Elementary particles/quantum entities exhibit properties of both particles and waves
• Heisenberg Uncertainty Principle: The position and momentum of a particle cannot both be precisely determined simultaneously
• Quantum Entanglement: Two or more particles become linked, so the state of one instantaneously influences the other, regardless of distance
• Quantum Superposition: A quantum system can exist in multiple states simultaneously until measured