PowerPoint PresentationHomework #8Quiz #5Chapter 5 Equilibrium of Rigid BodiesEquilibrium of Rigid BodiesSlide 6Equilibrium EquationsSlide 8Slide 9Free Body DiagramImportance of FBDChapter 5 Equilibrium ExamplesME 221 Lecture 22 1ME 221 StaticsLecture #22Sections 5.1 – 5.4ME 221 Lecture 22 2Homework #8•Chapter 9 problems:–42, 43, 50 & 55•Chapter 5 problems:–11, 13, 16, 20, 24 & 25–See Blackboard for additional information•Due Wednesday, October 30ME 221 Lecture 22 3Quiz #5•Friday, March 14ME 221 Lecture 22 4Chapter 5Equilibrium of Rigid BodiesME 221 Lecture 22 5Equilibrium of Rigid Bodies•Equilibrium equations•Free body diagrams•Modeling supports•ProblemsME 221 Lecture 22 6•Newton’s Second law states that if there is a net force acting on the body, then this will cause motion of the rigid body.•If there is no motion, then the object is said to be in equilibrium.Equilibrium of Rigid BodiesME 221 Lecture 22 7Equilibrium EquationsWhen the force system is replaced by a resultant force and moment that are zero, the rigid body is in equilibrium.~ ~0 and 0F M  The moment equation is new and differentiates particle from rigid body equilibrium.0 00 00 0x xy yz zF MF MF M      ME 221 Lecture 22 8Examples of supports:•rollers•smooth surfaces•rockers•clamps•slots•collars•cables•links•fixed Supports for Rigid BodiesIf a rigid object is subjected to some set of forces but does not move, then its motion could be restrained by a normal force exerted by the ground, a wall or from fixing the object with some support.ME 221 Lecture 22 9Support Reactions• If the support prevents translation in a given direction, then a force is developed on the member in that direction. Likewise, if a rotation is prevented, then a couple moment is exerted on the member.• See Figures 5.1 and 5.2 (supports for rigid bodies subjected to 2-D and 3-D force systems)ME 221 Lecture 22 10Free Body Diagram•Draw the body separate from all other bodies (including ground).•Draw the magnitudes and directions of all external forces acting on the body.–No need to scale arrow size•Include necessary dimensions of the body–Dimensions are needed for summing moments•Draw the positive sense of the coordinate system used to write out equilibrium equations–Include: applied loads, reactions due to supports, and the weight of the object.ME 221 Lecture 22 11Importance of FBD•The FBD is at least half of an equilibrium problem.ME 221 Lecture 22 12Chapter 5 Equilibrium