3.4 materials

Cards (28)

  • what is a tensile force?
    a force that produces extension
  • what is a compressive force?
    a force that shortens an object
  • when does tensile deformation occur?
    when a tensile force is applied
  • when does compressive deformation occur?
    when a compressive force is applied
  • what is Hooke's law?
    when the force applied to a material is directly proportional to its extension
  • what is the spring/force constant?
    k , measure of stiffness of a material
  • what is elastic deformation/limit ?
    material will return to its original shape after force is removed. materials sometimes follow hooke's law up to the elastic limit
  • what is plastic deformation?
    material has undergone permanent structural changes and therefore will not return to original shape after force is removed
  • what does area under a Fx graph represent?
    work done
  • what graph is this?
    loading and unloading graph for a metal wire
  • what graph is this?
    loading and unloading graph for polythene
  • what does change in area under a loading-unloading graph represent?
    thermal energy transfer to surroundings
  • what is tensile stress?
    stress = force / cross-sectional area
  • what is the unit of tensile stress?
    Pa
  • what is tensile strain?
    strain = extension / original length
  • what is the unites for tensile strain?
    no units
  • what does this graph represent?
    stress strain graph for a ductile material
  • what doe the points on this graph represent?
    P = limit of proportionality
    E = elastic limit
    Y1 = upper yield point (where material expands rapidly)
    Y2 = lower yield point (where material expands rapidly)
    UTS = ultimate tensile strength
    B = breaking point (point of fracture)
  • what is UTS?
    ultimate tensile strength is the maximum stress a material can withstand before reaching its breaking point
  • what is a strong material?
    material with a high UTS
  • what is young's modulus? 

    ratio of stress to strain
    young modulus = tensile stress/ tensile strain
  • what are the units for young modulus?
    pascals
  • what is this graph?
    stress strain graph for a polymeric material - polythene
  • what is this graph?
    stress strain graph for rubber
  • what is this graph?
    stress strain graph for brittle material
  • what is this graph?
    loading and unloading graph of a rubber band
  • how to work out force/spring constant of springs in parallel?
    add them together
  • how to work out force/spring constant of springs in series?
    add their inverses together to give 1/Ktotal