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2 definitions found
 for Virtual velocity
From The Collaborative International Dictionary of English v.0.48 :

  Velocity \Ve*loc"i*ty\, n.; pl. Velocities. [L. velocitas,
     from velox, -ocis, swift, quick; perhaps akin to volare to
     fly (see Volatile): cf. F. v['e]locit['e].]
     [1913 Webster]
     1. Quickness of motion; swiftness; speed; celerity; rapidity;
        as, the velocity of wind; the velocity of a planet or
        comet in its orbit or course; the velocity of a cannon
        ball; the velocity of light.
        [1913 Webster]
     Note: In such phrases, velocity is more generally used than
           celerity. We apply celerity to animals; as, a horse or
           an ostrich runs with celerity; but bodies moving in the
           air or in ethereal space move with greater or less
           velocity, not celerity. This usage is arbitrary, and
           perhaps not universal.
           [1913 Webster]
     2. (Mech.) Rate of motion; the relation of motion to time,
        measured by the number of units of space passed over by a
        moving body or point in a unit of time, usually the number
        of feet passed over in a second. See the Note under
        [1913 Webster]
     Angular velocity. See under Angular.
     Initial velocity, the velocity of a moving body at
        starting; especially, the velocity of a projectile as it
        leaves the mouth of a firearm from which it is discharged.
     Relative velocity, the velocity with which a body
        approaches or recedes from another body, whether both are
        moving or only one.
     Uniform velocity, velocity in which the same number of
        units of space are described in each successive unit of
     Variable velocity, velocity in which the space described
        varies from instant to instant, either increasing or
        decreasing; -- in the former case called accelerated
        velocity, in the latter, retarded velocity; the
        acceleration or retardation itself being also either
        uniform or variable.
     Virtual velocity. See under Virtual.
        [1913 Webster]
     Note: In variable velocity, the velocity, strictly, at any
           given instant, is the rate of motion at that instant,
           and is expressed by the units of space, which, if the
           velocity at that instant were continued uniform during
           a unit of time, would be described in the unit of time;
           thus, the velocity of a falling body at a given instant
           is the number of feet which, if the motion which the
           body has at that instant were continued uniformly for
           one second, it would pass through in the second. The
           scientific sense of velocity differs from the popular
           sense in being applied to all rates of motion, however
           slow, while the latter implies more or less rapidity or
           quickness of motion.
           [1913 Webster]
     Syn: Swiftness; celerity; rapidity; fleetness; speed.
          [1913 Webster]

From The Collaborative International Dictionary of English v.0.48 :

  Virtual \Vir"tu*al\ (?; 135), a. [Cf. F. virtuel. See Virtue.]
     1. Having the power of acting or of invisible efficacy
        without the agency of the material or sensible part;
        potential; energizing.
        [1913 Webster]
              Heat and cold have a virtual transition, without
              communication of substance.           --Bacon.
        [1913 Webster]
              Every kind that lives,
              Fomented by his virtual power, and warmed. --Milton.
        [1913 Webster]
     2. Being in essence or effect, not in fact; as, the virtual
        presence of a man in his agent or substitute.
        [1913 Webster]
              A thing has a virtual existence when it has all the
              conditions necessary to its actual existence.
        [1913 Webster]
              To mask by slight differences in the manners a
              virtual identity in the substance.    --De Quincey.
        [1913 Webster]
     Principle of virtual velocities (Mech.), the law that when
        several forces are in equilibrium, the algebraic sum of
        their virtual moments is equal to zero.
     Virtual focus (Opt.), the point from which rays, having
        been rendered divergent by reflection of refraction,
        appear to issue; the point at which converging rays would
        meet if not reflected or refracted before they reach it. 
     Virtual image. (Optics) See under Image.
     Virtual moment (of a force) (Mech.), the product of the
        intensity of the force multiplied by the virtual velocity
        of its point of application; -- sometimes called virtual
     Virtual velocity (Mech.), a minute hypothetical
        displacement, assumed in analysis to facilitate the
        investigation of statical problems. With respect to any
        given force of a number of forces holding a material
        system in equilibrium, it is the projection, upon the
        direction of the force, of a line joining its point of
        application with a new position of that point indefinitely
        near to the first, to which the point is conceived to have
        been moved, without disturbing the equilibrium of the
        system, or the connections of its parts with each other.
        Strictly speaking, it is not a velocity but a length.
     Virtual work. (Mech.) See Virtual moment, above.
        [1913 Webster]

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