ThermalEnergy.PNG|frame|right|1. Particles (atoms or molecules) are moving towards each other. This is kinetic energy. 2. The particles are close to each other and their kinetic energy has been converted into the potential energy of electromagnetic repulsion between the electons of the atoms. 3. The particles have accelerated away from each other and their energy is again kinetic.]]

Thermal energy is the internal energy of a thermodynamic system at equilibrium. The flow of thermal energy from one system to another is called heat. If the systems are at different temperatures then part of the thermal energy flow can be converted into work.

Thermal energy is a measure of the total vibrational energy in all the molecules and atoms in a certain substance. Thermal energy is composed of both kinetic and potential energy. The kinetic energy is from the random motion of the particles, and the potential energy originates from the repulsive electromagnetic force between the electrons of atoms that are close to each other.

See also

• Combustion
• Laws of thermodynamics
• Thermodynamics
• Energy

Thermodynamics | Heat

Tepelná energie | Energía térmica | Énergie thermique | אנרגיה תרמית | Energia termiczna