Thermal energy
From Wikipedia, the free encyclopedia
Thermal energy is the sum of the sensible energy and latent energy.
Contents |
[edit] Internal energy
Internal energy – the sum of all microscopic forms of energy of a system. It is related to the molecular structure and the degree of molecular activity and may be viewed as the sum of kinetic and potential energies of the molecules; it consists of the following types of energies:[1]
| Type | Composition of Internal Energy (U) |
|---|---|
| Sensible energy | the portion of the internal energy of a system associated with kinetic energies (molecular translation, rotation, and vibration; electron translation and spin; and nuclear spin) of the molecules. |
| Latent energy | the internal energy associated with the phase (i.e. solid, liquid, or gas), of a system/material. |
| Chemical energy | the internal energy associated with the atomic bonds in a molecule. |
| Nuclear energy | the tremendous amount of energy associated with the strong bonds within the nucleus of the atom itself. |
| Energy interactions | those types of energies not stored in the system (e.g. heat transfer, mass transfer, and work), but which are recognized at the system boundary as they cross it, which represent gains or losses by a system during a process. |
[edit] Definitions
[edit] System of N particles
According to the equipartition theorem, it is possible to define thermal energy. In a system of N molecules, each with f degrees of freedom, and if there are no other (non-quadratic) temperature-dependent forms of energy, then the total thermal energy of the system is:[2]
To note, Uthermal is almost never the total energy of a system; for instance, there can be static energy that doesn't change with temperature, such as bond energy or rest energy (E=mc2).
[edit] Other definitions
Thermal Energy comes from the movement of atoms and molecules in matter.
Thermal energy per particle is also called the average translational kinetic energy possessed by free particles given by equipartition of energy.[3]
Thermal energy is the difference between the internal energy of an object and the amount that it would have at absolute zero.[citation needed] It includes the quantity of kinetic energy due to the motion of the internal particles of an object, and is increased by heating and reduced by cooling.
In a monatomic ideal gas, the thermal energy is exactly given by the kinetic energy of the constituent particles.[citation needed]
[edit] See also
[edit] References
- ^ Cengel, Yungus, A.; Boles, Michael (2002). Thermodynamics - An Engineering Approach, 4th ed.. McGraw-Hill, 17-18. ISBN 0-07-238332-1.
- ^ Schroeder, Daniel, R. (2000). Thermal Physics. New York: Addison Wesley Longman. ISBN 0201380277.
- ^ Thermal energy – Hyperphysics
