Heat

Definition

Heat is a form of energy transfer between systems or objects with different temperatures, moving from the higher temperature system to the lower temperature one. It is measured in joules (J) or calories (cal).

5 Must Know Facts For Your Next Test

1. Heat flows naturally from hot objects to cold ones until thermal equilibrium is reached.
2. The specific heat capacity of a substance determines how much heat energy is required to change its temperature.
3. There are three primary methods of heat transfer: conduction, convection, and radiation.
4. The first law of thermodynamics states that the total energy in a closed system is conserved; it can be transformed but not created or destroyed.
5. The unit of heat in the International System of Units (SI) is the joule (J), but calories are also commonly used.

Review Questions

• What are the three primary methods of heat transfer?
• How does heat flow between two objects with different temperatures?
• What does the first law of thermodynamics state regarding energy?

Related terms

Conduction:

The process by which heat energy is transmitted through collisions between neighboring molecules or atoms.

Convection:

The transfer of heat by the movement of fluids (liquids or gases) caused by differences in temperature and density within the fluid.

Radiation:

\text{The transfer of energy through electromagnetic waves without involving particles.}