Consider a particle A acted upon by several coplanar forces, i.e., by
several forces contained in the same plane ( Fig. 2.14 a ). Since the
forces considered here all pass through A , they are also said to be
concurrent. The vectors representing the forces acting on A may be
added by the polygon rule ( Fig. 2.14 b ). Since the use of the polygon
rule is equivalent to the repeated application of the parallelogram
law, the vector R thus obtained represents the resultant of the given
concurrent forces, i.e., the single force which has the same effect onWe 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 the original 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 of components. 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
resolved into 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 the triangle 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, both components 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 and drawing 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
graphically or co
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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