The Energy Principle

Claimed by lakshitha

The energy principle is a broad equation that can be used to describe the changes in the different types of energy and any work that acts on a system or the transfer of heat into a system. There are many different types of energy, some of which include Kinetic Energy, Potential Energy, Chemical Energy, Rest Energy, Thermal Energy, etc.

The Main Idea

There are many ways to use the energy principle; most of the problems you will encounter will have no work acting on the system and no transfer of heat, thus E_sys,initial = E_sys,final. Other problems will involve only work acting on the system and no heat. It's important to identify what your system is before making any assumptions about its energy and whether there is any transfer of heat or any work acting on it. It's also useful to note that all objects have rest energy and a object has kinetic energy if it is moving; but, since rest energy is only changed when there is a change in mass of the object, it can usually be disregarded in any calculations. There are also different types of potential energy: Spring Potential Energy, Gravitational Potential Energy, Electric Potential Energy, and Gravitational Potential Energy near the surface of the Earth. Potentially Energy is only included if there is more than one object in your choice of system. For example, a system consisting of one proton and one electron would have Electric Potential Energy.

. For any multi-particle system, you have to take into account the potential energy between each of the objects.

A Mathematical Model

[math]\displaystyle{ {∆E} = {Q + W} }[/math] where [math]\displaystyle{ {Q} }[/math] is heat and [math]\displaystyle{ {W} }[/math] is the amount of work acting on the system.

[math]\displaystyle{ E=mc^2 }[/math] - Rest Energy

[math]\displaystyle{ KE=\frac{1}{2}mv² }[/math]
- Kinetic Energy

Potential Energy Equations:

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A Computational Model

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Examples

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Connectedness

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History

Thermodynamics was brought up as a science in the 18th and 19th centuries. However, it was first brought up by Galilei, who introduced the concept of temperature and invented the first thermometer. G. Black first introduced the word 'thermodynamics'. Later, G. Wilke introduced another unit of measurement known as the calorie that measures heat. The idea of thermodynamics was brought up by Nicolas Leonard Sadi Carnot. He is often known as "the father of thermodynamics". It all began with the development of the steam engine during the Industrial Revolution. He devised an ideal cycle of operation. During his observations and experimentations, he had the incorrect notion that heat is conserved, however he was able to lay down theorems that led to the development of thermodynamics. In the 20th century, the science of thermodynamics became a conventional term and a basic division of physics. Thermodynamics dealt with the study of general properties of physical systems under equilibrium and the conditions necessary to obtain equilibrium.

See also

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References

https://www.grc.nasa.gov/www/k-12/airplane/thermo0.html http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thereq.html https://www.grc.nasa.gov/www/k-12/airplane/thermo2.html http://www.phys.nthu.edu.tw/~thschang/notes/GP21.pdf http://www.eoearth.org/view/article/153532/