Materials topic 4 Flashcards
Hooke’s law
extension is proportional to force
F =
kx
what is k in hooke’s law
stiffness or spring constant
a material will show elastic deformation up to
its elastic limit
a material will show plastic deformation up tp its elastic limit and plastic deformation
beyond it
is the deformation is elastic
the material returns to its original shape once forces are removed
if the deformation is plastic
the material is permanently stretched
what is the limit of proportionality
point at which hooke’s law stops being obeyed
what is the elastic limit
if exceeded, the material will be permanently stretched
stiffness =
force/extension
tensile stress =
force/cross-sectional area
tensile strain =
change in length/original length
what is breaking stress
the point at which the material breaks due to great stress
what is UTS
ultimate tensile stress - the maximum stress a material can withstand
what do UTS and B depend on
temperature
what is the area under a force:extension graph
elastic strain energy
young modulus =
stress/strain
what is the young modulus used to measure
the stiffness of a material
what does the gradient of a stress:strain graph give
young modulus
what is the yield point
point after which the material stretches without extra load
density =
mass/volume
pressure =
force/area
extra pressure =
depth(h) x density x g
archimedes principle upthrust =
weight of fluid displaced
stokes law F=
6 x pi x viscosity x r x v
stoke’s law only applies to
small objects moving slowly with laminar flow
what is laminar flow
flow pattern where all parts of the fluid are flowing ion the same direction
what does stokes law find
viscous drag
viscosity =
(2r^2)(g)(Bdensity - Ldensity) / 9v
