What is internal energy?

Internal Energy

In thermodynamics, the internal energy is the total energy contained by a thermodynamic system. It is the energy needed to create the system, but excludes the energy to displace the system's surroundings, any energy associated with a move as a whole, or due to external force fields. Internal energy has two major components, kinetic energy and potential energy. The kinetic energy is due to the motion of the system's particles (translations, rotations, vibrations), and the potential energy is associated with the static rest mass energy of the constituents of matter, static electric energy of atoms within molecules or crystals, and the static energy of chemical bonds. The internal energy of a system can be changed by heating the system or by doing work on it; the first law of thermodynamics states that the increase in internal energy is equal to the total heat added and work done by the surroundings. If the system is isolated, its internal energy cannot change.

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Some articles on internal energy:

Conjugate Variables (thermodynamics) - Overview
... Just as a small increment of energy in a mechanical system is the product of a force times a small displacement, so an increment in the energy of a thermodynamic system can be expressed as the sum of the ... Pressure differences force a change in volume dV, and their product is the energy lost by the system due to work ... differences drive changes in entropy, and their product is the energy transferred by heat transfer ...
Properties of Explosions - Evolution of Heat
... former, slow combustion converts more of the internal energy (i.e ... detonation) instead converts more internal energy into work on the surroundings (i.e ... less internal energy converted into heat) c.f ...
Strain (chemistry)
... molecule experiences strain when its chemical structure undergoes some stress which raises its internal energy in comparison to a strain-free reference compound ... The internal energy of a molecule consists of all the energy stored within it ... A strained molecule has an additional amount of internal energy which an unstrained molecule does not ...
Clausius–Duhem Inequality in Terms of Specific Internal Energy
... The inequality can be expressed in terms of the internal energy as where is the time derivative of the specific internal energy (the internal energy per unit mass), is ... This inequality incorporates the balance of energy and the balance of linear and angular momentum into the expression for the Clausius–Duhem inequality ... to a Cartesian coordinate system , Hence, From the balance of energy Therefore, Rearranging ...
Internal Energy - History
... mechanical work he was doing on the system was converted to thermal energy ... Specifically, he found that 4185.5 joules of energy were needed to raise the temperature of a kilogram of water by one degree Celsius ...

Famous quotes containing the words energy and/or internal:

    I say, stamping the words with emphasis,
    Drink from here energy and only energy,
    Stephen Spender (1909–1995)

    The real essence, the internal qualities, and constitution of even the meanest object, is hid from our view; something there is in every drop of water, every grain of sand, which it is beyond the power of human understanding to fathom or comprehend. But it is evident ... that we are influenced by false principles to that degree as to mistrust our senses, and think we know nothing of those things which we perfectly comprehend.
    George Berkeley (1685–1753)