12 Static Equilibrium and Elasticity
12 Chapter Review
Key Terms
- breaking stress (ultimate stress)
- value of stress at the fracture point
- bulk modulus
- elastic modulus for the bulk stress
- bulk strain
- (or volume strain) strain under the bulk stress, given as fractional change in volume
- bulk stress
- (or volume stress) stress caused by compressive forces, in all directions
- center of gravity
- point where the weight vector is attached
- compressibility
- reciprocal of the bulk modulus
- compressive strain
- strain that occurs when forces are contracting an object, causing its shortening
- compressive stress
- stress caused by compressive forces, only in one direction
- elastic
- object that comes back to its original size and shape when the load is no longer present
- elastic limit
- stress value beyond which material no longer behaves elastically and becomes permanently deformed
- elastic modulus
- proportionality constant in linear relation between stress and strain, in SI pascals
- equilibrium
- body is in equilibrium when its linear and angular accelerations are both zero relative to an inertial frame of reference
- first equilibrium condition
- expresses translational equilibrium; all external forces acting on the body balance out and their vector sum is zero
- gravitational torque
- torque on the body caused by its weight; it occurs when the center of gravity of the body is not located on the axis of rotation
- linearity limit (proportionality limit)
- largest stress value beyond which stress is no longer proportional to strain
- normal pressure
- pressure of one atmosphere, serves as a reference level for pressure
- pascal (Pa)
- SI unit of stress, SI unit of pressure
- plastic behavior
- material deforms irreversibly, does not go back to its original shape and size when load is removed and stress vanishes
- pressure
- force pressing in normal direction on a surface per the surface area, the bulk stress in fluids
- second equilibrium condition
- expresses rotational equilibrium; all torques due to external forces acting on the body balance out and their vector sum is zero
- shear modulus
- elastic modulus for shear stress
- shear strain
- strain caused by shear stress
- shear stress
- stress caused by shearing forces
- static equilibrium
- body is in static equilibrium when it is at rest in our selected inertial frame of reference
- strain
- dimensionless quantity that gives the amount of deformation of an object or medium under stress
- stress
- quantity that contains information about the magnitude of force causing deformation, defined as force per unit area
- stress-strain diagram
- graph showing the relationship between stress and strain, characteristic of a material
- tensile strain
- strain under tensile stress, given as fractional change in length, which occurs when forces are stretching an object, causing its elongation
- tensile stress
- stress caused by tensile forces, only in one direction, which occurs when forces ar