14.1 Thermal Equilibrium

Direction of Transfer of Thermal Energy

Direction of Thermal Energy Transfer

Thermal Energy is always transferred from a region of higher temperature to a region of lower temperature.

Example

A thermometer placed in hot and cold water

When a thermometer initially at $25^o\mathrm{C}$ is placed in:

1. $90^{\circ }\mathrm{C}$ Water

• Thermal energy flows from the water (higher temperature) into the thermometer (lower temperature).

2. $5^{\circ }\mathrm{C}$ Water

• Thermal energy flows form the thermometer (higher temperature) into the water (lower temperature).

Thermal Equililbrium

Thermal Equilibrium

Two regions or objects are in thermal equilibrium when they are at the same temperature and there is no net transfer of thermal energy between them.

Example

Two regions reaching thermal equilibrium