Moment of a couple

moment of a couple
    n 1: given two equal and opposite forces, the product of the
         force and the distance between them
    

Moment \Mo"ment\, n. [F. moment, L. momentum, for movimentum
   movement, motion, moment, fr. movere to move. See {Move}, and
   cf. {Momentum}, {Movement}.]
   1. A minute portion of time; a point of time; an instant; as,
      at that very moment.
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            In a moment, in the twinkling of an eye. --1 Cor.
                                                  xv. 52.
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   2. Impulsive power; force; momentum.
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            The moments or quantities of motion in bodies.
                                                  --Berkley.
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            Touch, with lightest moment of impulse,
            His free will.                        --Milton.
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   3. Importance, as in influence or effect; consequence; weight
      or value; consideration.
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            Matters of great moment.              --Shak.
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            It is an abstruse speculation, but also of far less
            moment and consequence of us than the others.
                                                  --Bentley.
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   4. An essential element; a deciding point, fact, or
      consideration; an essential or influential circumstance.
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   5. (Math.) An infinitesimal change in a varying quantity; an
      increment or decrement. [Obs.]
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   6. (Mech.) Tendency, or measure of tendency, to produce
      motion, esp. motion about a fixed point or axis.
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   {Moment of a couple} (Mech.), the product of either of its
      forces into the perpendicular distance between them.

   {Moment of a force}. (Mech.)
      (a) With respect to a point, the product of the intensity
          of the force into the perpendicular distance from the
          point to the line of direction of the force.
      (b) With respect to a line, the product of that component
          of the force which is perpendicular to the plane
          passing through the line and the point of application
          of the force, into the shortest distance between the
          line and this point.
      (c) With respect to a plane that is parallel to the force,
          the product of the force into the perpendicular
          distance of its point of application from the plane.
          

   {Moment of inertia}, of a rotating body, the sum of the mass
      of each particle of matter of the body into the square of
      its distance from the axis of rotation; -- called also
      {moment of rotation} and {moment of the mass}.

   {Statical moment}, the product of a force into its leverage;
      the same as {moment of a force} with respect to a point,
      line, etc.

   {Virtual moment}. See under {Virtual}.
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   Syn: Instant; twinkling; consequence; weight; force; value;
        consideration; signification; avail.
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