Kelvin Scale - T (in K) = θ (in °C) + 273, Boyle's Law - For a fixed mass of gas at constant temperature, Pressure × Volume is constant, Thermal Expansion - Most substances expand when heated because the particles vibrate more and take up more space, Specific Heat Capacity - The energy required to raise the temperature of 1 kg of a substance by 1 °C., Melting - Solid → Liquid, Boiling - Liquid → Gas (happens throughout the liquid at a fixed boiling point), Evaporation - Liquid → Gas (happens at the surface at any temperature), Conduction - The transfer of thermal energy through a material without the material itself moving, Conduction in metals - due to free electrons that gain kinetic energy and move through the metal, colliding with other electrons and ions, Conduction in non-metals - energy can only be transferred by the much slower process of vibrations being passed between neighbouring atoms, Convection - The transfer of thermal energy by the movement of a fluid (liquid or gas), Thermal Radiation - The transfer of energy by infrared (IR) waves. Does NOT require a medium (can travel through a vacuum), Dull, black surfaces - good emitters and good absorbers of IR radiation, Shiny, white surfaces - poor emitters and poor absorbers (good reflectors), Constant Temperature - when the rate of energy it absorbs equals the rate of energy it emits, Silvered walls of a vacuum flask - reduce thermal radiaton, Vacuum space between walls of flask - reduce thermal convection, Change of state - temperature stays constant as the energy is used to break intermolecular bonds, not raise kinetic energy, Evaporation causes cooling - most energetic molecules escape from the surface, lowering the average kinetic energy, Order of thermal expansion - gases > liquids > solids, Increasing gas temperature - increases gas pressure due to higher speed of particles, leading to more collisions, Temperature of a substance - The average kinetic energy of the particles in the substance, Absolute zero - -273 degrees Celcius, Pressure in gases - Caused by particles colliding with the walls of their container, Solids - Particles vibrate in fixed positions, packed closely in a regular pattern., Liquids - Particles are close together but can move past each other randomly, Gases - Particles are far apart, move very fast and randomly,

Unit 2: Thermal Physics - Definitions

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