11- materials Flashcards
what is density
mass per unit volume
density calculation
p= m/v
what is hookes law
- the force required to produce an extension is directly proportional to the extension up to the limit of proportionality
hookes law equation
F= K △L
What is the gradient of the straight line in force extension graphs?
the spring constant of the material
what is the end of the straight line region in a force extension graph?
the limit of proportionality
what is the area under the graph in a force extension graph
work done in the stretching of the material
what is the work done formula
w= F △l/2
how do you convert a mass to a force
F = mg
what happens to springs in parallel when an object is hung from them
they will both extend by the same amount regardless of spring constants
what’s the force acting on springs in parallel like
both/ all springs will experience a different force (unless identical spring constants)
what is the equation for weight in springs in parallel
w= (k1 + k2) △l
what is the equation for total spring constant for springs in parallel
k= k1 + k2
what happens to springs in series when an object is hung from them
both springs will support the load but will extend by different amounts (unless identical spring constants)
what’s the force in spring in series like
due to newtons 3rd law, there is an equal but opposite force
what is the equation for weight in springs in parallel
F1= K1 △l1
F2= K2 △l2
what is the equation for total spring constant in springs in series
1/K = 1/K1 + 1/K2
what does it mean when an object displays plastic behavior
it means a force has been applied to an object but once removed the object did not return to its original shape
what is tensile stress
the force per unit cross-sectional area
what is the equation for tensile stress
stress= F/A
what is tensile strain
the strain experienced by an object is the ratio of the extension to its original length
tensile strain equation
Ɛ = ΔL / Lo
what is young modulus
the ratio of stress over strain for a material. it is a measure of a solids stiffness
what is the young modulus equation
E= FL / A ΔL
what are brittle materials
materials which break easily, and have little of no plastic deformation
what is an example of an elastomer
rubber bands
what is the work done in an elastomer stress-strain graph
it is the area under the loading graph
what is the work done when a rubber band is returning to its original shape in an elastomer stress-strain graph
the area under the unloading graph
