College Physics Chapter 4 Key Terms
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acceleration
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the rate at which an object's velocity changes over a period of time
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carrier particle
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a fundamental particle of nature that is surrounded by a characteristic force field; photons are this of the electromagnetic force
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dynamics
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the study of how forces affect the motion of objects and systems
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external force
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a force acing on an object or system that originates outside of the object or system
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force field
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a region in which a test particle will experience a force
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force
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a push or pull on an object with a specific magnitude and direction' can be represented by vectors; can be expressed as a multiple of a standard force.
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free-body diagram
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a sketch showing all of the external forces acting on an object or system; the system is represented by a dot, and the forces are represented by vectors extending outward from the dot.
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free-fall
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a situation in which the only force acting on an object is the force due to gravity
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inertia
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the tendency of an object to remain at rest or remain in motion
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inertial frame of reference
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a coordinate system that is not accelerating; all forces acting in an inertial frame of reference are real forces, as opposed to fictitious forces that are observed de to a accelerating frame of reference.
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mass
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the quantity of matter in a substance; measured in kilograms
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Newton's first law of motion (law of inertia)
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a body at rest remains at rest, or, of in motion, remains in motion at a constant velocity unless acted on by a net external force
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Newton's second law of motion
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the net external force on an object with mass m is proportional to and in the same direction as the acceleration of the object, and inversely proportional to the mass; defined mathematically as F = ma
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Newton's third law of motion
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whenever one body exerts a force on a second body; the first body experiences a force that is equal in magnitude and opposite in direction to the force that the first body exerts.
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net external force
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the vector sum of all external forces acting on an object or system; causes a mass to accelerate
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normal force
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the force that a surface applies to an object to support the weight of the object; acts perpendicular to the surface on which the object rests
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system
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defined by the boundaries of an object or collection of objects being observed; all forces originating from outside of the system are considered external forces
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tension
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the pulling force that acts along a medium, especially a stretched flexible connector, such as a rope or cable; when a rope supports the weight of an object, the force on the object due to the rope is called a tension force.
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thrust
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a reaction force that pushes a body forward in response to a backward force; rockets, airplanes, and cars are pushed forward by this reaction force.
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weight
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the force w due to gravity acting on an object of mass; defined mathematically as: w = mg, where g is the magnitude and direction of the acceleration due to gravity.
