Application of Newton's LawsFREE-BODY DIAGRAMSRev. 0Page 5CP-04FREE-BODY DIAGRAMSIn studying the effect of forces on a body it is necessary to isolate the body anddetermine all forces acting upon it. This method of using a free-body diagram isessential in understanding basic and complex force problems.EO 1.2STATE the purpose of a free-bodydiagram.EO 1.3Given all necessary information, CONSTRUCT afree-body diagram.In solving a problem involving forces it is essential that Newton's laws are carefully fixed inmind and that these principles are applied literally and exactly. In applying these principlesit is essential that the body be isolated from all other bodies so that a complete and accurateaccount of all forces which act on this body may be considered. The diagram of such anisolated body with the representation of all external forces acting on it is called a Free-BodyDiagram. It has long been established that the free-body-diagram method is the key to theunderstanding of engineering problems. This is because the isolation of a body is the tool thatclearly separates cause and effect and focuses our attention to the literal application of aprinciple.Example:Consider the book resting on the table in Figure 1. Although the book isstationary, two forces are acting on the book to keep it stationary. One is theweight (W) of the book exerting a force down on the table. The other is theforce exerted up by the table to hold the book in place. This force is knownas the normal force (N) and is equal to the weight of the book. A normalforce is defined as any perpendicular force with which any two surfaces arepressed against each other. The free-body diagram for this situation,illustrated on the right side in Figure 1, isolates the book and presents theforces acting on the object.