Introduction to Physics

• Physics is a natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force.
• Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

Core Concepts

• Classical mechanics describes the motion of macroscopic objects.
• Thermodynamics deals with heat, work, and energy, and the relationships between them.
• Electromagnetism explains the interactions between electric charges and magnetic moments.
• Quantum mechanics describes the behavior of matter and energy at the atomic and subatomic levels.
• Relativity, including special and general relativity, describes the relationship between space, time, gravity, and the universe at large.

Classical Mechanics

• Kinematics describes the motion of objects without considering the causes of the motion (displacement, velocity, acceleration).
• Dynamics studies the forces that cause motion (Newton's laws of motion).
• Newton's 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 a force.
• Newton's Second Law: Force is equal to the rate of change of momentum. For constant mass, F = ma (force equals mass times acceleration).
• Newton's Third Law: For every action, there is an equal and opposite reaction.
• Work is the energy transferred to or from an object by means of a force acting on the object (Work = Force x Distance x cos(theta)).
• Energy can neither be created nor destroyed, but can be changed from one form into another (Law of Conservation of Energy).
• Power is the rate at which work is done or energy is transferred (Power = Work / Time).

Thermodynamics

• Describes the relationships between heat, work, and energy.
• Temperature is a measure of the average kinetic energy of the particles in a system.
• Heat is the transfer of energy between objects or systems due to a temperature difference.
• Zeroth Law of Thermodynamics: If two systems are separately in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.
• First Law of Thermodynamics: The change in internal energy of a system is equal to the heat added to the system minus the work done by the system (ΔU = Q - W).
• Second Law of Thermodynamics: The total entropy of an isolated system can only increase over time or remain constant in ideal cases.
• Third Law of Thermodynamics: As the temperature approaches absolute zero, the entropy of a system approaches a minimum or zero value.

Electromagnetism

• Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electromagnetic field.
• Electric field is the force per unit charge experienced by a test charge at a given point in space.
• Coulomb's Law: The electric force between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.
• Magnetic field is a field of force produced by moving electric charges.
• Ampère's Law: The magnetic field around a closed loop is proportional to the electric current passing through the loop.
• Faraday's Law of Induction: A changing magnetic field induces an electromotive force (EMF) or voltage in a circuit.
• Maxwell's Equations: A set of four equations that describe the behavior of electric and magnetic fields, and their interactions with matter.
• Electromagnetic waves are disturbances that propagate through space, carrying energy in the form of electric and magnetic fields.
• Light is an electromagnetic wave and propagates at a constant speed in a vacuum (c ≈ 3.00 x 10^8 m/s).

Quantum Mechanics

• Describes the behavior of matter and energy at the atomic and subatomic levels.
• Quantum mechanics demonstrates that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values (quantization).
• Wave-particle duality: Particles can exhibit both wave-like and particle-like properties.
• Heisenberg Uncertainty Principle: It is impossible to know both the position and momentum of a particle with perfect accuracy.
• Schrödinger equation describes how the quantum state of a physical system changes over time.
• Quantum entanglement is a phenomenon where two or more particles become linked together in such a way that they share the same fate, no matter how far apart they are.

Relativity

• Special relativity describes the relationship between space and time for observers in relative motion at constant velocity.
• The laws of physics are the same for all observers in uniform motion relative to one another (Principle of Relativity).
• The speed of light in a vacuum is the same for all observers, regardless of the motion of the light source (constancy of the speed of light).
• Time dilation: Time passes slower for moving objects relative to stationary observers.
• Length contraction: The length of a moving object appears shorter in the direction of motion to a stationary observer.
• Mass-energy equivalence: Energy and mass are interchangeable, with E=mc^2 (energy equals mass times the speed of light squared).
• General relativity describes gravity as a curvature of spacetime caused by mass and energy.
• Gravitational time dilation: Time passes slower in stronger gravitational fields.
• Black holes are regions of spacetime where gravity is so strong that nothing, not even light, can escape.
• Gravitational waves are ripples in spacetime caused by accelerating massive objects.

Units and Measurement

• The International System of Units (SI) is the standard system of units used in physics.
• The base units are meter (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for electric current, kelvin (K) for temperature, mole (mol) for amount of substance, and candela (cd) for luminous intensity.
• Derived units are combinations of base units.
• Scientific notation is used to express very large or very small numbers in a compact form.
• Significant figures indicate the precision of a measurement.

Problem Solving Strategies

• Read the problem carefully and identify what is being asked.
• Draw a diagram or sketch to visualize the problem.
• Identify the relevant physics principles and equations.
• List the known and unknown quantities.
• Solve the equations for the unknown quantities.
• Check the units and make sure the answer makes sense.