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 * //__Parallax:__//** When the position of an object shifts while viewed from different locations.
 * online definition of[| PARLAX]
 * [[image:http://farm1.static.flickr.com/31/64595009_a8b509b2eb.jpg?v=0 width="93" height="61"]]
 * [|glass parallax close up]


 * //__Parameter:__//** A factor that sets the limit of possible value.


 * Online definition of [|parameter]

Pascal:The Sl unit of pressure [|online definition of pascal] = = __//**period**//__:In chemistry, a horizontal row of elements in the periodic table [|online defintion for period]
 * Gadl's photostream
 * [|Smarties: Inverted Double Spiral (-1,2)]
 * Leo Reynolds
 * [|pressure gauge]
 * [[image:http://farm1.static.flickr.com/16/23178762_0e94ccf117.jpg?v=0 width="154" height="108"]]
 * denn
 * [|periodic table-final version]

__//**Periodic:**//__ describes something that occurs or repeats at regular intervals.

__//**periodic law:**//__ the law that states that the reapeating chemical and physical properties of elements change periodically with the atomic numbers of the elements.

__//**pH:**//__a value that is used to express the acidity or basicity of a system.

RBertieg [|Solar eclipse partial phase and corona] __//**Physical:**//__of or having to do with matter or the body
 * //__Phase:__//**the change in the sunlit area of one celestial body as seen from another celestial body.

__//**Physical change:**//__ a change of matter from one form to another without a change in chemical properties.

__//**Physical property:**//__ a characteristic of a substance that does not involve a chemical change, such as density, color, or hardness.

__//**Plasma:**//__ in physical science, a state of matter that starts as a gas and then becomes ionized; it consist of free moving ions and electrons, it takes on an electric charge, and its properties differ from the properties of a solid, liquid, or gas. __//**Precipitate:**//__a solid that is produced as a result of a chemical reaction in solution.

__//**Predict:**//__to stay ahead of time.

__//**Principle:**//__basic law, rule, or belief.
 * //__Pressure:__//**the amount of force exerted per unit area of surface.

__//**Process:**//__a set of steps, events, or changes.

__//**Product:**//__a substance that forms in a chemical reaction.

__//**Progade rotation:**//__the counterclockwise spin of a planet or moon as seen from above the planet's north pole; rotation in the same direction as the sun's rotation.

__//**Projectile motion:**//__the curved path that an object follows when thrown, launched, or otherwise projected near the surface of earth. __//**Protein:**//__a molecule that is made up of amino acids and that is needed to build and repair body structures and to regulate processes in the body.

__//**Proton:**//__ a subatomic particle that has a positive charge and that is located in the nucleus of an atom;the number of protons in the nucleus is the atomic number, which determines the identity of an element.

__//**Pure substance:**//__a sample of matter, either a single element or a single compound, that has definite chemical and physical properties.