Introduction to Physics

• Physics is a natural science studying matter, its basic parts, its motion through space and time, and related things like energy and force.
• Physics is a core science that seeks to understand the behavior of the universe.
• The scientific method is applied in physics to create and test ideas based on observations from experiments.
• Physics is the discipline that develops physical theories
• Physical laws are commonly written as short mathematical equations.
• Physical theories are generally well-tested and widely used
• A physical law is a scientific idea based on things seen in experiments.
• A statement becomes a physical law only after many tests without any conflicting evidence.
• Physics is related to other sciences, especially chemistry.
• Mathematics informs physics.
• Physics is important to all natural sciences.
• Subdivisions within physics include:
  • Classical mechanics
  • Electromagnetism
  • Thermodynamics
  • Quantum mechanics
  • Relativity
• Classical mechanics studies the motion of large objects.
• Electromagnetism studies how electric and magnetic fields interact.
• Thermodynamics studies heat and energy.
• Quantum mechanics studies how matter acts at the atomic level.
• Relativity studies the structure of spacetime.
• Physics finds use in engineering, medicine, and materials science, among other fields.
• Physical laws apply everywhere, though they can be simpler to use in some situations.
• Current physics research includes string theory and quantum gravity.
• Many physics problems are too complex to solve perfectly.

Classical Mechanics

• Classical mechanics explains how large things move, like rockets, machines, planets, and stars.
• It gives very correct answers when looking at big things moving slower than light.
• Classical mechanics uses Newton's laws of motion.
• Newton's laws of motion state:
  • Objects stay still or move steadily unless a force acts on them.
  • An object's acceleration relates to the force on it and its mass (F = ma).
  • When one object pushes on another, the second object pushes back equally hard in the opposite direction.
• Classical mechanics studies energy, work, and power.

Electromagnetism

• Electromagnetism is the study of how electric and magnetic fields interact.
• Electric charges create electric and magnetic fields.
• Changing magnetic fields make electric fields, and changing electric fields make magnetic fields.
• Electromagnetism is described by Maxwell's equations.
• Maxwell's equations connect electric and magnetic fields to the charges and currents that create them.
• Electromagnetism says that light is an electromagnetic wave.
• Technologies such as motors, generators, and radios use electromagnetism.

Thermodynamics

• Thermodynamics studies heat and energy.
• Thermodynamics is based on the laws of thermodynamics.
• Laws of thermodynamics state:
  • Energy is always conserved.
  • Entropy always goes up.
  • As temperature nears absolute zero, a system's entropy approaches a constant value.
• Thermodynamics is applied in engines, refrigerators, and power plants.

Quantum Mechanics

• Quantum mechanics studies how matter behaves at the atomic level.
• Quantum mechanics says that energy, momentum, and other things are quantized.
• Quantum mechanics uses the Schrödinger equation.
• The Schrödinger equation tells how a quantum system changes over time.
• Quantum mechanics explains the photoelectric and Compton effects, which classical mechanics cannot.
• Quantum mechanics is used in lasers, transistors, and nuclear weapons.

Relativity

• Relativity studies the structure of spacetime.
• Relativity includes special and general relativity.
• Special relativity relates space and time.
• Special relativity has two rules:
  • Physics laws are the same for all observers moving at a constant speed.
  • Light speed is constant for everyone, no matter how the light source moves.
• General relativity deals with gravity.
• General relativity explains gravity as curves in spacetime.
• Relativity is used in GPS satellites and particle accelerators.

Key Concepts

• Energy is the ability to do work.
• Force is a push or pull that can change motion.
• Mass measures the amount of matter.
• Velocity is how fast position changes.
• Acceleration is how fast velocity changes.
• Momentum is mass times velocity.
• Angular momentum measures an object's rotation.
• Electric charge is a basic property of matter.
• Electric current is the flow of electric charge.
• Electric field surrounds electric charges
• Magnetic field surrounds moving electric charges.
• Wavelength is the distance between wave crests or troughs.
• Frequency is the number of waves passing a point each second.
• Temperature measures the average energy of particles in a system.
• Entropy measures disorder in a system.

Scientific Method

• The scientific method is a way to learn about the natural world.
• The steps of the scientific method are:
  • Observation
  • Hypothesis
  • Prediction
  • Experiment
  • Analysis
  • Conclusion

Physics is a natural science that studies matter, energy, and their interactions. It aims to understand the fundamental laws governing the universe through observation, experimentation, and mathematical formulation. Physics is closely related to other sciences like chemistry and plays a vital role in the natural sciences.