CHAPTER 6 Flashcards
EXTENSION
the increase in length of an object when a tensile force is exerted on it
TENSILE FORCES
equal and opposite forces acting on an material to stretch it
COMPRESSIVE FORCE
two or more forces together that reduce the length or volume of an object
COMPRESSION
the decrease in length of an object when a compressive force is exerted on it
TENSILE DEFORMATION
a change in the shape of an object due to its tensile forces
COMPRESSIVE DEFORMATION
a change in the shape of an object due to its compressive forces
FORCE- EXTENSION GRAPH
a graph of force against extension, with the area under the graph equal to the work done on the material
ELASTIC LIMIT
the value of stress or force beyond which elastic deformation becomes plastic deformation, and the material or object will no longer return to its original shape and size when the stress or force is removed
ELASTIC DEFORMATION
a reversible change in the shape of an object due to a compressive or tensile force- removal of stress or force will return the object to its original shape and size
HOOKES LAW
the force applied is directly proportional to the extension of of the spring unless the limit of proportionality is exceeded
FORCE CONSTANT
a quantity determined by dividing force by extension for an object obeying hookes law- called constant of proportionality ‘k’, measured in Nm-1
STIFFNESS
the ability of an object to restrict deformation
ELASTIC POTENTIAL ENERGY
the energy stored in an object because of its deformation
LOADING CURVE
a force- extension graph
HYSTERESIS LOOP
a loop shaped plot obtained when loading and unloading a material produce different deformations
TENSILE STRAIN
the extension per unit length
TENSILE STRESS
the force per unit cross sectional area, measured in Pa
DUCTILE
property of a material that has a large plastic region in a stress- strain graph, so can be drawn into wires
LIMIT OF PROPORTIONALITY
the value of stress or force beyond which stress is no longer directly proportional to strain
YIELD POINT
a point on a stress- strain graph beyond which the deformation is no longer entirely elastic
ULTIMATE TENSILE STRENGTH
the maximum stress that a material can withstand before it breaks
BRAKING STRENGTH
the stress value a the point of fracture, calculated by dividing the breaking force by the cross sectional area
STRONG MATERIAL
a material with a large value for the ultimate tensile strength
YOUNG MODULUS
the ratio of tensile stress to tensile strain when these quantities are directly proportional to each other, measured in Pa
BRITTLE
property of a material that does not show plastic deformation and deforms very little under high stress
POLYMERIC
description of a material comprising of long- chain molecules, such as rubber, which may show large strains
