Thermal Physics: notes

Particles and states

• Solid: particles vibrate in fixed places, close together.
• Liquid: particles are close but slide past each other.
• Gas: particles are far apart and move fast in random directions.
• Gas pressure: caused by particles hitting the container walls. At constant temperature, pV stays constant (Boyle's law).

Heat

• Temperature: how hot something is. Heat: energy that flows from hot to cold.
• Specific heat capacity: the energy needed to raise 1 kg by 1 °C. Q = mcΔT.
• Latent heat: energy to change state with no change in temperature, such as melting or boiling.
• Expansion: solids, liquids and gases expand when heated.

Heat transfer

• Conduction: particles pass energy along a solid. Metals conduct best.
• Convection: hot fluid rises and cool fluid sinks, in liquids and gases.
• Radiation: infrared waves that need no material. Dull black surfaces absorb and emit best; shiny surfaces reflect.