Ch 9: Solids & Elastic Moduli Flashcards
(21 cards)
3 phases of matter
solid
liquid
gas
a solid has a definite _______ and ________
shape and volume
a liquid has a definite _______, but assumes the ______ of its container
volume, shape
a gas takes on the _______ and _________ of its container
shape, volume
what is a fluid
a substance that can flow
liquids & gases
what is an elastic response
something that is deformed by an applied force will return to its original dimensions or shape when the force is removed
what forces allow for elasticity of a solid
interatomic forces – like springs
stress definition
a measure of the force causing the deformation
strain definition
a relative measure of the deformation caused by a stressor
stress equation
stress = F/A (N/m^2)
applied force per unit cross-sectional area
tensile stress
an elongating tension (pulling apart)
compressional stress
a shortening tension (pushing together)
tensile strain
ratio of the change in length to the original length
strain equation
strain = | deltaL | / Lo –> | L - Lo | / Lo
fractional change in length
elastic modulus
stress/strain (N/m^2)
3 types: Young’s, shear, bulk
Young’s modulus
change in length (tension or compression)
Y=stress/strain
elastic limit
the tension at which a material can be returned to its original dimensions
beyond the elastic limit, permanent deformation occurs
shear modulus (S) / modulus of rigidity
occurs when deformation is due to a force that is tangential to the surface area
shape changes without changing volume
bulk modulus (B)
when a force directed inward acts over the entire surface of an object (pressure from a fluid)
volume changes, but not shape
do gases have bulk moduli?
yes, but use the compressibility
compressibility (k)
k = 1/B
reciprocal of bulk modulus
