Temperature, Heat, and Thermal Energy

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Thermal Energy Noun

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[thur-muhl en-er-jee]

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Thermal Energy

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The total sum of the kinetic and potential energies of all the individual particles that constitute an object.

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Example: This image shows that as a heat source adds thermal energy to water, the water's particles (shown in magnified views) move faster and spread apart.

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Kinetic Energy Noun

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[ki-net-ik en-er-jee]

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Kinetic Energy

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The energy possessed by an object or its constituent particles as a result of being in motion.

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Example: This image shows that kinetic energy is the energy of motion, as a soccer ball moves after being kicked. The ball's speed contributes to its kinetic energy.

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Potential Energy Noun

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[po-ten-shuhl en-er-jee]

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Potential Energy

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The stored energy within particles resulting from their internal bonds and their interactions with one another.

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Example: Stretching a rubber band stores elastic potential energy. This is a form of mechanical potential energy, which is different from the potential energy of particles in thermal energy.

Front

Temperature Noun

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[tem-per-uh-cher]

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Temperature

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A quantitative measure that is directly related to the average kinetic energy of the particles within an object.

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Example: This diagram shows that at a low temperature, particles have low energy and are close together. At a high temperature, particles have more energy and spread apart.

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Kinetic Theory Noun

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[ki-net-ik thee-uh-ree]

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Kinetic Theory

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A scientific theory explaining the relationship between the random motions of particles and the macroscopic properties of a substance.

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Example: This image shows that matter is made of particles. In solids, they are tightly packed; in liquids, they can move past each other; in gases, they are far apart.

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Heat (Q) Noun

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[heet]

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Heat (Q)

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The spontaneous transfer of thermal energy from a region of higher temperature to a region of lower temperature.

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Example: This diagram shows that heat is the flow of energy from a hotter object (red block) to a colder object (blue block), driven by a temperature difference.

Front

Thermal Conduction Noun

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[thur-muhl kon-duhk-shuhn]

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Thermal Conduction

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The transfer of thermal energy through a material by the direct collision and interaction of its constituent particles.

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Example: High-energy particles from a hot region collide with and transfer energy to low-energy particles in a cold region through direct contact.

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Convection Noun

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[kon-vek-shuhn]

Back

Convection

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The transfer of thermal energy in a fluid, such as a liquid or gas, through the bulk movement of heated particles.

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Example: Heat from below causes warmer, less dense water to rise, while cooler, denser water sinks, creating a circular flow called a convection current.

Front

Radiation Noun

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[rey-dee-ey-shuhn]

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Radiation

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The transfer of energy through space in the form of electromagnetic waves, which does not require a medium.

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Example: The Sun transfers thermal energy to the Earth through space as electromagnetic waves, a process called radiation.

Front

Thermal Equilibrium Noun

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[thur-muhl ee-kwi-lib-ree-uhm]

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Thermal Equilibrium

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The state where two objects in contact have the same temperature, resulting in no net flow of thermal energy.

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Example: This diagram shows a hot object (100°) and a cold object (0°) exchanging heat over time until they both reach the same temperature (50°).