Classical Mechanics Overview

Classical Mechanics

• Classical mechanics describes the motion of macroscopic objects, typically those much larger than atoms.
• It assumes that space and time are continuous and absolute.
• Key figures in classical mechanics include Newton and Galileo.
• Newton's laws of motion form the foundation of classical mechanics:
  • First law: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
  • Second law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. (F=ma)
  • Third law: For every action, there is an equal and opposite reaction.
• Key concepts:
  • Force: A push or pull that can change the motion of an object.
  • Mass: A measure of an object's inertia, its resistance to changes in motion.
  • Acceleration: The rate at which an object's velocity changes.
  • Momentum: The product of an object's mass and velocity.
• Different types of forces:
  • Gravitational force: The force of attraction between any two objects with mass.
  • Electromagnetic force: The force between charged particles.
  • Strong nuclear force: The force that holds protons and neutrons together in the nucleus of an atom.
  • Weak nuclear force: The force involved in certain types of radioactive decay.
• Energy concepts, work and power:
  • Work: The product of force and displacement in the direction of the force.
  • Power: The rate at which work is done.
  • Kinetic energy: The energy of motion.
  • Potential energy: Stored energy due to position or configuration.
  • Conservation of energy: Total energy in an isolated system remains constant.

Thermodynamics

• Thermodynamics describes the relationship between heat, work, and other forms of energy.
• Key concepts:
  • Heat: A form of energy transferred between objects due to a temperature difference.
  • Temperature: A measure of the average kinetic energy of the particles in a substance.
  • Internal energy: The sum of all molecular kinetic and potential energies within a substance.
  • Zeroth law of thermodynamics: If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.
  • First law of thermodynamics: Energy cannot be created or destroyed; it can only be transferred or changed from one form to another.
  • Second law of thermodynamics: The total entropy of an isolated system can only increase over time, or remain constant in ideal cases of reversible processes.
  • Third law of thermodynamics: The entropy of a perfect crystal at absolute zero temperature is zero.
• Different processes:
  • Isothermal process: A process occurring at constant temperature.
  • Adiabatic process: A process with no heat transfer.
  • Isobaric process: A process occurring at constant pressure.
  • Isochoric process: A process occurring at constant volume.
• Applications of thermodynamics:
  • Heat engines: Devices that convert heat into work.
  • Refrigerators: Devices that transfer heat from a cold region to a hot region.

Electromagnetism

• Electromagnetism describes the relationship between electricity and magnetism.
• Key concepts:
  • Electric field: A region of space around a charged object where a force is exerted on other charged objects.
  • Magnetic field: A region of space around a magnet or a moving charged object where a force is exerted on other magnets or moving charged objects.
  • Electric current: A flow of electric charge.
  • Electromagnetic waves: Waves that are created by the oscillation of electric and magnetic fields, travel at the speed of light.
• Key laws:
  • Coulomb's law: Describes the force between two point charges.
  • Gauss's law: Relates the electric flux through a closed surface to the enclosed electric charge.
  • Ampere's law: Relates the magnetic field around a closed loop to the electric current passing through the loop.
  • Faraday's law of induction: Describes the induced electromotive force (EMF) in a conductor by a changing magnetic field.
• Applications of electromagnetism:
  • Electric motors: Convert electrical energy to mechanical energy.
  • Generators: Convert mechanical energy to electrical energy.
  • Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays: electromagnetic waves with varying frequencies and wavelengths.

Optics

• Optics deals with the study of light and its behavior.
• Key concepts:
  • Reflection: The bouncing of light off a surface.
  • Refraction: The bending of light as it passes from one medium to another.
  • Diffraction: The spreading of light as it passes through an aperture or around an obstacle.
  • Interference: The superposition of light waves, resulting in either constructive or destructive interference patterns.
  • Polarization of light: A property of light waves that can be described as the vibration orientation of the electric field.
• Types of lenses and mirrors:
  • Convex lenses: Converge light rays.
  • Concave lenses: Diverge light rays.
  • Plane mirrors: Reflect light rays, producing an image that is the same size as the object.
  • Spherical mirrors: Reflect light rays, forming images that can be real or virtual.
• Applications of optics:
  • Telescopes: Collect and magnify light from distant objects.
  • Microscopes: Produce magnified images of small objects.
  • Cameras: Capture images of objects by focusing light on a sensor.
  • Lasers: Produce highly directional, coherent beams of light with many applications.

Modern Physics

• Modern physics covers topics beyond classical physics, including:
  • Quantum mechanics: Describes the behavior of matter and energy at the atomic and subatomic levels.
    • Key principles: Quantization of energy, wave-particle duality, Heisenberg's uncertainty principle.
  • Relativity: Describes the relationship between space and time, developed by Einstein.
    • Key theories: Special relativity (constant speed of light), General relativity (gravity as curvature of spacetime).