Key Concepts in Physics

Branches of Physics
- Classical Mechanics: Study of motion and forces (e.g., Newton's Laws).
- Thermodynamics: Study of heat transfer, energy, and work.
- Electromagnetism: Study of electric charges, magnetic fields, and their interactions.
- Quantum Mechanics: Study of matter and energy at atomic and subatomic levels.
- Relativity: Study of the effects of gravity and motion on space and time (Einstein's theories).
Fundamental Laws
- Newton's Laws of Motion:
  1. An object at rest stays at rest; an object in motion stays in motion unless acted upon by a force.
  2. Force equals mass times acceleration (F = ma).
  3. For every action, there is an equal and opposite reaction.
- Laws of Thermodynamics:
  1. The energy of an isolated system is constant (conservation of energy).
  2. Entropy of an isolated system always increases (disorder over time).
  3. Absolute zero cannot be achieved (temperature limits).
Key Measurements
- Velocity: Speed with direction (vector).
- Acceleration: Change in velocity over time.
- Force: Interaction that causes a change in motion (N=kg·m/s²).
- Work: Energy transfer via force over a distance (W=F·d).
- Energy Types: Kinetic, potential, thermal, chemical, and nuclear.
Waves and Sound
- Properties: Wavelength, frequency, amplitude, and speed.
- Sound: Longitudinal wave, requires a medium to travel.
Light and Optics
- Electromagnetic spectrum: Range of all types of light, including visible, infrared, ultraviolet, X-rays, and gamma rays.
- Reflection: Bouncing back of light from a surface.
- Refraction: Bending of light as it passes from one medium to another.
Modern Physics
- Quantum Theory: Describes the behavior of particles at the quantum level, introducing concepts like wave-particle duality and uncertainty principle.
- General and Special Relativity: Addresses high-speed motion (special) and the effect of gravity on time and space (general).
Key Formulas
- Kinematics: ( v = u + at ), ( s = ut + \frac{1}{2}at^2 ), ( v^2 = u^2 + 2as )
- Conservation of Energy: ( KE + PE = constant )
- Electric Force: ( F = k \frac{q_1q_2}{r^2} ) (Coulomb's Law)
Important Concepts
- Matter: Anything that has mass and takes up space.
- Forces: Push or pull interactions (e.g., gravitational, electromagnetic, nuclear).
- Conservation Laws: Energy, momentum, and charge are conserved in isolated systems.

These notes cover foundational concepts and terminology within the field of physics, providing a framework for further study and understanding.

Branches of Physics

Classical Mechanics studies how objects move and interact with forces. A key example is Newton's Laws of Motion.
Thermodynamics focuses on heat transfer, energy, and work. It explains how energy transforms and transfers.
Electromagnetism explores electric charges, magnetic fields, and their interactions. It's fundamental to understanding electricity and magnetism.
Quantum Mechanics dives into the behavior of matter and energy at the atomic and subatomic level. It describes the world at the smallest scales.
Relativity examines how gravity and motion affect space and time. Einstein's theories of special and general relativity are key examples.

Fundamental Laws

Newton's Laws of Motion:
- First Law: An object at rest stays at rest and an object in motion stays in motion (at a constant speed and direction) unless acted upon by a force.
- Second Law: Force is equal to mass times acceleration (F = ma).
- Third Law: For every action (force), there is an equal and opposite reaction (force).
Laws of Thermodynamics:
- First Law: Energy of an isolated system remains constant. This is known as the conservation of energy.
- Second Law: Entropy, a measure of disorder, always increases in an isolated system.
- Third Law: Absolute zero temperature cannot be achieved. This is the lowest possible temperature.

Key Measurements

Velocity: Speed with a direction (vector). It describes how fast an object moves and in what direction.
Acceleration: Change in velocity over time. It describes how quickly an object's velocity changes.
Force: Interaction that causes a change in motion. It's measured in Newtons (N).
Work: Energy transferred via force over a distance. It's measured in Joules (J).
Energy Types:
- Kinetic Energy is the energy of motion.
- Potential Energy is stored energy related to position or configuration.
- Thermal Energy is related to the internal energy of an object due to temperature.
- Chemical Energy is stored in the bonds of molecules.
- Nuclear Energy is stored in the nucleus of an atom.

Waves and Sound

Properties of Waves:
- Wavelength: Distance between two crests or troughs.
- Frequency: Number of waves passing a point per second.
- Amplitude: Maximum displacement from equilibrium.
- Speed: Distance traveled by a wave in a unit of time.
Sound: Sound travels as a longitudinal wave, which means particles in the medium oscillate parallel to the direction of wave propagation. Sound requires a medium to travel.

Light and Optics

Electromagnetic Spectrum: Range of all types of light (electromagnetic radiation), including visible light, infrared, ultraviolet, X-rays, and gamma rays.
Reflection: Bouncing back of light from a surface.
Refraction: Bending of light as it passes from one medium to another.

Modern Physics

Quantum Theory: Explains the behavior of particles at the quantum level. It introduces key concepts like wave-particle duality and the Heisenberg uncertainty principle.
Relativity:
- Special Relativity: Addresses high-speed motion and the effects of relative speeds on time and space.
- General Relativity: Addresses the effect of gravity on time and space.

Key Formulas

Kinematics:
- (\ v = u + at ) - Final velocity (v) equals initial velocity (u) plus acceleration (a) multiplied by time (t).
- ( s = ut + \frac{1}{2}at^2 ) - Displacement (s) equals initial velocity (u) multiplied by time (t) plus one-half times acceleration (a) multiplied by time (t) squared.
- ( v^2 = u^2 + 2as ) - Final velocity (v) squared equals initial velocity (u) squared plus two times acceleration (a) multiplied by displacement (s).
Conservation of Energy: ( KE + PE = constant ) - Kinetic energy (KE) plus potential energy (PE) remains constant in an isolated system.
Electric Force: ( F = k \frac{q_1q_2}{r^2} ) - The electric force (F) between two charges (q1 and q2) is proportional to the product of the charges and inversely proportional to the squared distance (r) between them.

Important Concepts

Matter: Anything that has mass and takes up space.
Forces: Push or pull interactions, such as gravitational, electromagnetic, nuclear, and strong force.
Conservation Laws: Fundamental laws in physics that state that certain quantities are conserved in isolated systems, such as energy, momentum, and charge.