Materials (AS) Flashcards
What is density?
Mass per unit volume.
State Hooke’s Law.
The extension of a stretched object is proportional to the force applied to it.
F = k ΔL
For which range does Hooke’s Law apply?
Until the limit of proportionality.
What is the breaking stress?
The maximum stress that an object can withstand before it breaks.
What does ‘brittle’ mean?
An object that will show very little strain before reaching its breaking stress.
What does ‘elastic behaviour’ mean?
If a material deforms with elastic behaviour, it will return to its original shape when the forces are removed.
What is the elastic limit?
The point at which, if you increase the load, the material will be permanently stretched.
What does ‘plastic behaviour’ mean?
If a material deforms with plastic behaviour, it will not return to its original shape when the forces are removed.
What is ‘tensile stress’?
The amount of force acting per unit area.
σ = F/A
Units: Pa or Nm^-2
What is ‘tensile strain’?
The ratio of an object’s extension to its original length.
It is a ratio of two lengths and so has no unit.
What is the Young Modulus?
A measure of the stiffness of a material.
The ratio of stress to strain for a given material.
Its unit is the Pascal (Pa).
