Law of conservation of energy: Difference between revisions
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[[es:Ley de conservación de la energía]] | |||
<onlyinclude>The '''law of conservation of energy''' states that [[energy]] can neither be created nor destroyed - only converted from one form of energy to another.</onlyinclude> This means that a [[system]] always has the same amount of [[energy]], unless it's added from the outside. This is particularly confusing in the case of [[non-conservative force]]s, where energy is converted from [[mechanical energy]] into [[thermal energy]], but the overall energy does remain the same. The only way to use energy is to [[energy transformations|transform energy]] from one form to another. | <onlyinclude>The '''law of conservation of energy''' states that [[energy]] can neither be created nor destroyed - only converted from one form of energy to another.</onlyinclude> This means that a [[system]] always has the same amount of [[energy]], unless it's added from the outside. This is particularly confusing in the case of [[non-conservative force]]s, where energy is converted from [[mechanical energy]] into [[thermal energy]], but the overall energy does remain the same. The only way to use energy is to [[energy transformations|transform energy]] from one form to another. | ||
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*[[Heat]] | *[[Heat]] | ||
*[[Carnot efficiency]] | *[[Carnot efficiency]] | ||
*Or explore a | *Or explore a [http://energyeducation.ca/encyclopedia/Special:Random| random page] | ||
To learn more about the physics of the law of conservation of energy, please see [http://hyperphysics.phy-astr.gsu.edu/hbase/conser.html#coneng hyperphysics] or for how this relates to chemistry please see UC Davis's [http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/Laws_of_Thermodynamics/First_Law_of_Thermodynamics/Conservation_of_Energy chem wiki]. | To learn more about the physics of the law of conservation of energy, please see [http://hyperphysics.phy-astr.gsu.edu/hbase/conser.html#coneng hyperphysics] or for how this relates to chemistry please see UC Davis's [http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/Laws_of_Thermodynamics/First_Law_of_Thermodynamics/Conservation_of_Energy chem wiki]. | ||
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Latest revision as of 17:46, 21 August 2022
The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside. This is particularly confusing in the case of non-conservative forces, where energy is converted from mechanical energy into thermal energy, but the overall energy does remain the same. The only way to use energy is to transform energy from one form to another.
The amount of energy in any system, then, is determined by the following equation:
- is the total internal energy of a system.
- is the initial internal energy of a system.
- is the work done by or on the system.
- is the heat added to, or removed from, the system.
It is also possible to determine the change in internal energy of the system using the equation:
This is also a statement of the first law of thermodynamics.
While these equations are extremely powerful, they can make it hard to see the power of the statement. The takeaway message is that energy cannot be created from nothing. Society has to get energy from somewhere, although there are many sneaky places to get it from (some sources are primary fuels and some sources are primary energy flows).
Early in the 20th century, Einstein figured out that even mass is a form of energy (this is called mass-energy equivalence). The amount of mass directly relates to the amount of energy, as determined by the most famous formula in physics:
- is the amount of energy in an object or system.
- is the mass of the object or system.
- is the speed of light, roughly .
For Further Reading
To learn more about the physics of the law of conservation of energy, please see hyperphysics or for how this relates to chemistry please see UC Davis's chem wiki.