# Dictionary - P

• parable: Plane curve whose points are equidistant from a fixed point (focus) and a fixed line (guideline) or curve resulting from a section made in a cone by a plane parallel to the generatrix. Curve that a projectile describes.
• parallel: Designates lines or surfaces that always keep the same distance from each other throughout their length.
• parsec: Unit of measurement for interstellar space, equal to a distance having a heliocentric parallax of 1 second or 206,265 times the radius of Earth's orbit, or 3.26 light years, or 30.8 trillion kilometers.
• particle: It is a body endowed with mass, of negligible size and can be considered as a point.
• pendulum: Heavy body suspended from a fixed point that oscillates freely in a reciprocating motion. Something that has been done or happens at regular intervals.
• period: Time elapsed between two events or two dates. Time it takes a star to describe its orbit. Any given or undetermined time frame.
• perpendicular: The straight line is said to form equal adjacent angles with one another or with those belonging to the same plane to the point where it intersects that plane.
• Weight: Measure of the force with which bodies are attracted to the central point of the earth. Pressure exerted by a body on the obstacle that directly opposes its fall. Gravity inherent in bodies.
• plan: It is said of such a surface that the whole line joining two of its points is fully understood on that surface.
• Cartesian plane: Each of the imaginary vertical surfaces, which vary in depth perspective, and on which the figures of a frame may be arranged. The foreground is that of the figures that seem closest to the observer.
• magnetic pole: Each of the two points of a magnet or magnetized body in which the magnetic flux density is more or less concentrated. Each of two terminals of a battery or a dynamo, related in such a way that if the two are connected by an external conductor, an electrical current from the pole having greater potential will flow to the other.
• Score: Geometric element considered without dimensions, only with position.
• power: Work done in the unit of time.
• potential: It is said to be energy dependent on the position or nature of the body. Amount of positive electrical charge of a body to ground or to a grounded conductor, considered zero. Ability to work in relation to factors that facilitate or hinder action.
• potentiometer: Apparatus for measuring differences in electrical potential. Part designed to control voltage in electronic circuits.
• pressure: The application of a force to a body by another body in contact with it. Action that a body exerts on its surface. Action of one force against another that opposes it. Force exerted by a fluid in all directions, always measured by surface unit.
• principle: Fundamental law, doctrine or meaning on which others are based or from which others are derived. Rule or law exemplified in natural phenomena, in the construction or operation of a machine or mechanism, in the realization of a system.
• propagation: Transmission of a vibrating energy form (light, sound, radio wave) through space or along a path.
• propulsion: It is the movement created from a force that gives momentum. Propulsion can be created in any act of pushing forward or giving momentum.