Thermal Physics

Vocabulary flashcards covering the fundamentals of thermal physics, heat transfer mechanisms, particle models, phase changes, and core thermal formulas.

Thermal physics

The study of heat, temperature, and how thermal energy moves between objects.

Temperature

How hot or cold something is, linked to the average kinetic energy of particles; measured in degrees Celsius ($^\circ\text{C}$) or kelvin ($\text{K}$).

Heat

Energy transferred from a hotter object to a cooler object, measured in joules ($\text{J}$).

Solids (particle model)

State of matter in which particles vibrate in fixed positions.

Liquids (particle model)

State of matter in which particles are close together but move past each other.

Gases (particle model)

State of matter in which particles are far apart and move freely.

Conduction

Heat transfer through a material, especially solids (e.g., a metal spoon heating up).

Convection

Heat transfer by movement of liquids or gases, where warm fluid rises and cooler fluid sinks.

Radiation

Heat transfer by electromagnetic waves where no medium is needed (e.g., the Sun heating Earth).

Thermal expansion and contraction

The behavior wherein most materials expand when heated and contract when cooled (e.g., gaps left in railway tracks to allow for expansion).

Melting

The change of state from solid to liquid.

Freezing

The change of state from liquid to solid.

Evaporation/boiling

The change of state from liquid to gas.

Condensation

The change of state from gas to liquid.

Sublimation

The change of state directly from solid to gas.

Change of state temperature behavior

Temperature stays constant for a pure substance at constant pressure while energy changes particle arrangement.

Thermal energy formula

$Q = mc\Delta T$, where $Q$ is energy ($\text{J}$), $m$ is mass ($\text{kg}$), $c$ is specific heat capacity ($\text{J/kg}\,^\circ\text{C}$), and $\Delta T$ is temperature change ($^\circ\text{C}$ or $\text{K}$).

Latent heat formula

$Q = mL$, where $Q$ is energy ($\text{J}$), $m$ is mass ($\text{kg}$), and $L$ is specific latent heat ($\text{J/kg}$).

Celsius to Kelvin conversion

$$\text{K} = ^\circ\text{C} + 273.15$$

Insulators

Materials that slow down heat transfer.

Dull black surface

A good absorber and good emitter of thermal radiation.

Shiny light surface

A poor absorber and poor emitter of thermal radiation.