Cuerpos Rigidos

2.6 RESOLUTION OF A FORCE INTO COMPONENTS
We have seen that two or more forces acting on a particle may be
replaced by a single force which has the same effect on the particle.Conversely, a single force F acting on a particle may be replaced by
two or more forces which, together, have the same effect on the
particle. These forces are called the components of theoriginal force
F , and the process of substituting them for F is called resolving the
force F into components.
Clearly, for each force F there exist an infinite number of possible
sets ofcomponents. Sets of two components P and Q are the
most important as far as practical applications are concerned. But,
even then, the number of ways in which a given force F may be
resolvedinto two components is unlimited ( Fig. 2.15 ). Two cases are
of particular interest:
1. One of the Two Components, P , Is Known. The second component,
Q , is obtained by applying thetriangle rule and joining
the tip of P to the tip of F ( Fig. 2.16 ); the magnitude and
direction of Q are determined graphically or by trigonometry.
Once Q has been determined, bothcomponents P and Q
should be applied at A .
2. The Line of Action of Each Component Is Known. The magnitude
and sense of the components are obtained by applying the
parallelogram law anddrawing lines, through the tip of F , parallel
to the given lines of action ( Fig. 2.17 ). This process leads
to two well-defined components, P and Q , which can be determined
graphicallyor computed trigonometrically by applying
the law of sines.
Many other cases can be encountered; for example, the direction
of one component may be known, while the magnitude of theother component is to be as small as possible (see Sample Prob. 2.2).
In all cases the appropriate triangle or parallelogram which satisfies
the given conditions is drawn

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