## Thursday, July 24, 2008

### Physics

"Law" of Gravity: Newton developed his "Law of Gravity" to explain the attractive force between a pair of masses. In recent years, it has become clear that this is not the whole story, as Einstein's theory of general relativity has provided a more comprehensive explanation for the phenomenon of gravity.

Conservation of Mass-Energy:
The total energy in a closed or isolated system is constant, no matter what happens. Another law stated that the mass in an isolated system is constant. When Einstein discovered the relationship E=mc2, in other words that mass was a manifestation of energy, the law was said to refer to the conservation of mass-energy, which says the total of both is retained, although some may change forms. The ultimate example of this is a nuclear explosion, where mass transforms into energy.

Conservation of Momentum:
The total momentum in a closed or isolated system remains constant. An alternative of this is the law of angular momentum.

Laws of Thermodynamics:
The laws of thermodynamics are actually specific manifestations of the law of conservation of mass-energy as it relates to thermodynamic processes.

* The zeroeth law of thermodynamics makes the notion of temperature possible.
* The first law of thermodynamics demonstrates the relationship between internal energy, added heat, and work within a system.
* The second law of thermodynamics relates to the natural flow of heat within a closed system.
* The third law of thermodynamics states that it is impossible to create a thermodynamic process which is perfectly efficient.

Electrostatic Laws:
Coulomb's law and Gauss's law are formulations of the relationship between electrically charged particles to create electrostatic force and electrostatic fields. The formulas, it turns out, parallel the laws of universal gravitation in structure. There also exist similar laws relating to magnetism and electromagnetism as a whole.

Invariance of the Speed of Light:
Einstein's major insight, which led him to the Theory of Relativity, was the realization that the speed of light in a vacuum is constant and is not measured differently for observers in different inertial frames of reference, unlike all other forms of motion.
Modern Physics & Physical Laws:
In the realm of relativity and quantum mechanics, scientists have found that these laws still apply, although their interpretation requires some refinement to be applied, resulting in fields such as quantum electronics and quantum gravity. Care should be taken in applying them in these situations.

### Three Laws of Motion

* Newton's First Law of Motion states that in order for the motion of an object to change, a force must act upon it, a concept generally called inertia.
* Newton's Second Law of Motion defines the relationship between acceleration, force, and mass.
* Newton's Third Law of Motion states that any time a force acts from one object to another, there is an equal force acting back on the original object. If you pull on a rope, therefore, the rope is pulling back on you as well.

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"Victory belongs to the most persevering"

-Times-