Introduction to Physics

• Physics is the study of matter, energy, and their interactions
• It aims to understand the fundamental laws governing the universe

Branches of Physics

• Classical Mechanics: Deals with the motion of macroscopic objects under the influence of forces
• Thermodynamics: Deals with heat, work, and energy transfer
• Electromagnetism: Deals with electric and magnetic fields and their interactions
• Optics: Deals with the behavior and properties of light
• Quantum Mechanics: Deals with the behavior of matter at the atomic and subatomic level
• Relativity: Deals with the structure of spacetime and gravity

Mechanics

• Kinematics: Describes motion without considering its causes
• Dynamics: Describes motion considering its causes (forces)
• Statics: Deals with objects at rest or in equilibrium

Kinematics

• Displacement: Change in position of an object
• Velocity: Rate of change of displacement
• Average velocity: Total displacement divided by total time
• Instantaneous velocity: Velocity at a specific instant in time
• Acceleration: Rate of change of velocity
• Average acceleration: Change in velocity divided by change in time
• Instantaneous acceleration: Acceleration at a specific instant in time
• Uniform motion: Motion with constant velocity (zero acceleration)
• Equations of motion for uniform acceleration: v = u + at, s = ut + (1/2)at², v² = u² + 2as, where v is final velocity, u is initial velocity, a is acceleration, t is time, and s is displacement
• Projectile motion: Motion of an object under the influence of gravity
• Horizontal component of velocity remains constant in projectile motion (neglecting air resistance)
• Vertical component of velocity changes due to gravity in projectile motion
• Time of flight, maximum height, and range are important parameters in projectile motion

Dynamics

• Force: An interaction that can cause a change in an object's motion
• Newton's First Law (Law of Inertia): 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.
• Inertia is the tendency of an object to resist changes in its state of motion
• Mass is the measure of inertia
• Newton's Second Law: F = ma (Force equals mass times acceleration)
• Newton's Third Law: For every action, there is an equal and opposite reaction.
• Weight: Force of gravity acting on an object (W = mg, where g is the acceleration due to gravity)
• Friction: Force that opposes motion between surfaces in contact
• Static friction: Force that prevents an object from starting to move
• Kinetic friction: Force that opposes the motion of a moving object
• Tension: Force transmitted through a string, rope, cable, or wire when it is pulled tight by forces acting from opposite ends
• Normal force: The force exerted by a surface on an object in contact with it, perpendicular to the surface
• Free-body diagram: A diagram showing all the forces acting on an object

Work and Energy

• Work: Force applied over a distance (W = Fd cosθ, where θ is the angle between force and displacement)
• Kinetic Energy: Energy of motion (KE = (1/2)mv²)
• Potential Energy: Stored energy due to position or condition
• Gravitational Potential Energy: PE = mgh (where h is height)
• Elastic Potential Energy: PE = (1/2)kx² (where k is spring constant and x is displacement from equilibrium)
• Work-Energy Theorem: The net work done on an object is equal to the change in its kinetic energy (Wnet = ΔKE)
• Power: Rate at which work is done (P = W/t)
• Conservation of Energy: Total energy of an isolated system remains constant
• Energy can be transformed from one form to another, but it cannot be created or destroyed

Momentum and Collisions

• Momentum: Product of mass and velocity (p = mv)
• Impulse: Change in momentum (J = Δp = FΔt)
• Conservation of Momentum: In a closed system, the total momentum remains constant
• Collisions: Interactions between objects involving exchange of momentum and energy
• Elastic Collision: Kinetic energy is conserved
• Inelastic Collision: Kinetic energy is not conserved
• Perfectly Inelastic Collision: Objects stick together after the collision

Rotational Motion

• Angular displacement: Change in angular position (θ)
• Angular velocity: Rate of change of angular displacement (ω)
• Angular acceleration: Rate of change of angular velocity (α)
• Torque: A force that causes rotation (τ = rFsinθ, where r is the distance from the axis of rotation to the point where the force is applied, and θ is the angle between r and F)
• Moment of Inertia: Resistance to rotational motion (I)
• Rotational Kinetic Energy: KE = (1/2)Iω²
• Angular Momentum: L = Iω
• Conservation of Angular Momentum: If no external torque acts on a system, the total angular momentum remains constant

Waves

• Wave: A disturbance that transfers energy through a medium
• Transverse Wave: Particles oscillate perpendicular to the direction of wave propagation
• Longitudinal Wave: Particles oscillate parallel to the direction of wave propagation
• Wavelength: Distance between two successive crests or troughs (λ)
• Frequency: Number of waves passing a point per unit time (f)
• Period: Time for one complete wave to pass a point (T = 1/f)
• Wave Speed: v = fλ
• Amplitude: Maximum displacement of a particle from its equilibrium position
• Superposition: When two or more waves overlap
• Interference: Superposition resulting in increased or decreased amplitude
• Constructive Interference: Waves add up, resulting in larger amplitude
• Destructive Interference: Waves cancel each other out, resulting in smaller amplitude
• Diffraction: Bending of waves around obstacles or through openings
• Doppler Effect: Change in frequency due to relative motion between source and observer

Thermodynamics

• Temperature: Measure of the average kinetic energy of the particles in a substance
• Heat: Transfer of energy due to temperature difference
• Specific Heat Capacity: Amount of heat required to raise the temperature of 1 kg of a substance by 1 degree Celsius
• Heat Transfer: Conduction, convection, and radiation
• Conduction: Transfer of heat through direct contact
• Convection: Transfer of heat through the movement of fluids
• Radiation: Transfer of heat through electromagnetic waves
• Laws of Thermodynamics:
• Zeroth Law: If two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.
• First Law: Change in internal energy equals heat added to the system minus work done by the system (ΔU = Q - W)
• Second Law: Entropy of an isolated system always increases
• Third Law: Entropy of a system approaches a constant value as the temperature approaches absolute zero

Electricity and Magnetism

• Electric Charge: Property of matter that causes it to experience a force when placed in an electromagnetic field
• Coulomb's Law: F = k(q1q2/r²), where F is the electric force, q1 and q2 are the charges, r is the distance between the charges, and k is Coulomb's constant
• Electric Field: Region around a charged object where another charged object experiences a force
• Electric Potential: Potential energy per unit charge
• Current: Rate of flow of electric charge (I = ΔQ/Δt)
• Voltage: Electric potential difference (V = IR, Ohm's Law)
• Resistance: Opposition to the flow of current
• Magnetic Field: Region around a magnet or current-carrying conductor where a magnetic force is exerted
• Electromagnetic Induction: Production of an electromotive force (voltage) across a conductor when it is exposed to a varying magnetic field