EquilibriumandElasticity.pptVIP

Chapter 12:  Equilibrium and Elasticity Conditions Under Which a Rigid Object is in Equilibrium Problem-Solving Strategy Elasticity Equilibrium: Conditions of Equilibrium: The center or gravity: How is the center of gravity of an object determined? Problem-Solving Strategy: Elasticity Young’s Modulus:  Elasticity in Length Shear Modulus:  Elasticity in Shape Bulk Modulus:  Elasticity in Volume Summary: Sample Problem 12-3: * An object at equilibrium is either ... at rest and staying at rest (i.e., static equilibrium) , or in motion and continuing in motion with the constant velocity and constant angular momentum. For the object in equilibrium, the linear momentum ( ) of its center of mass is constant. the angular momentum ( ) about its center of mass, or any other point, is constant. Net force: Net torque: Conditions of equilibrium: Another requirements for static equilibrium: The gravitational force on a body effectively acts at a single point, called the center of gravity (cog) of the body. the center of mass of an object depends on its shape and its density the center of gravity of an object depends on its shape, density, and the external gravitational field. Does the center of gravity of the body always coincide with the center of mass (com)? Yes, if the body is in a uniform gravitational field. The center of gravity (cog) of a regularly shaped body of uniform composition lies at its geometric center. The (cog) of the body can be located by suspending it from several different points. The cog is always on the line-of-action of the force supporting the object. cog Define the system to be analyzed Identify the forces acting on the system Draw a free-body diagram of the system and show all the forces acting on the system, labeling them and making sure that their points of application and lines of action are correctly shown. Write down two equilibrium requirem