5.1 Thermal Physics

Definitions & Equations

Zeroth Law of Thermodynamics

When object A is in thermal equilibrium with object B, and object B is in thermal equilibrium with object C, object A is in thermal equilibrium with object C.

Heat

Flow of thermal energy (hot to cold)

Internal energy

The sum of the kinetic and potential energies for all particles in a system

Absolute zero

The lowest temperature possible, particles have minimum internal energy

Assumptions for the model of kinetic theory (gases)

1. Molecules occupy negligible volume compared to the gas

2. There are no electrostatic forces of attraction between the molecules of gas except during collisions

3. All collisions are perfectly elastic

4. Time taken for collisions to occur is negligible

5. Large number of molecules

Boyle's Law

Pressure is inversely proportional to volume at a constant temperature

Charles's Law

Volume is proportional to temperature at a constant pressure

Pressure Law

Pressure is directly proportional to temperature at a constant volume

Temperature

Average kinetic energy of one particle

Thermal energy

The total kinetic energy of all particles in a system/of an object

Which phase(s) can have rotational and vibrational kinetic energy?

Solids, liquids, diatomic gases

Which phase(s) can have translational kinetic energy?

Gases

First law of thermodynamics

Change in internal energy = energy transferred thermally to material + work done on material