By possessing an understanding of Newton’s Laws, following these three laws ofgraphical solutions, and understanding vector algebra you can solve mostengineering static problems.
Systems of Force Systems of force acting on objectsin equilibrium can be classified as either concurrent or nonconcurrent and aseither coplanar or noncoplanar. This gives us four general categories ofsystems. The first category, concurrent-coplanar forces occur when the lines ofaction of all forces lie in the same plane and pass through a common point. Figure 1 illustrates a concurrent-coplanar force in such that F1, F2, and W alllie in the same plane (the paper) and all their lines of action have point O incommon. To determine the resultant of concurrent force systems, you can use thePythagorean theorem, the law of sines, or the law of cosines as outlined in theprevious chapter.
Nonconcurrent-coplanar force is when the lines of action ofall forces lie in the same plane but do not pass through a common point asillustrated in figure 2. The magnitude and direction of the resultant force canbe determined by the rectangular component method using the first two equationsin figure 2, and the perpendicular distance of the line of action of R from theaxis of rotation of the body can be found using the third equation in figure 2. Concurrent-noncoplanar forces are when Application the lines of action of allforces pass through a common point and are not in the same plane. To find theresultant of these forces it is best to resolve each force into components alongthree axes that make angles of 90 degrees with each other. Nonconcurrent-noncoplanar forces are when the lines of action of all forces donot pass through a common point and the forces do not all lie in the same plane.
Stress When a restrained body is subject to external forces, there is a tendencyfor the shape of the body.
