Physics - Thermal physics (States of matter and Heat transfer)

The Kinetic Molecular Theory: Matter is made of particles in constant motion. In solids, particles vibrate about fixed positions; in liquids, they slide over each other; in gases, they move randomly at high speeds.

Brownian Motion: The random movement of microscopic particles (like smoke or pollen) in a fluid, providing evidence for the kinetic theory as they are bombarded by invisible atoms or molecules.

Thermal Expansion: Most substances expand when heated because their particles move faster and push further apart. This is quantified by the change in volume or length relative to the change in temperature $\Delta T$.

Internal Energy: The sum of the total microscopic kinetic energy and potential energy of the particles within a system.

Specific Heat Capacity ($c$): The energy required per unit mass to raise the temperature of a substance by $1^\circ C$. It is measured in $J/(kg\cdot^\circ C)$.

Latent Heat ($L$): The energy absorbed or released during a change of state (fusion or vaporization) without a change in temperature. $L_f$ is for melting/freezing, and $L_v$ is for boiling/condensing.

Conduction: The transfer of thermal energy through a substance by the vibration of atoms and the movement of delocalized electrons (primarily in metals).

Convection: The transfer of heat in fluids (liquids and gases) caused by the upward movement of less dense, warmer regions and the downward movement of denser, cooler regions.

Radiation: The transfer of energy by infrared electromagnetic waves. It does not require a medium and can travel through a vacuum. Dull black surfaces are the best emitters and absorbers, while shiny silver surfaces are the best reflectors.