solids under stress 1.5

• edge dislocation


  where there is an extra plane in the crystals
• how to work out the energy stored in a spring

  area under a f-x graph
• stress


  tension per unit cross sectional area
• strain


  extension per unit length due to applied stress
• how to calculate extension up to the elastic limit


  f=kx
• hookes law 


  tension in a spring or wire is proportional to its extension from its natural length provided the extension is not too great
• polymeric


  have very long molecules consisting of a large number of repeated monomers making a polymer
• amorphous


  have no long range order
• ductile fractures


  where the number of edge dislocations increases and causes the elongation of the metal which increases the stress at the neck
• crystalline


  solids with long range order, the particles are arranged in a lattice
• plastic deformation


  occurs when the dislocations move due to the large stress
• Youngs modulus 


  ratio of stress to strain for a material in the Hooke's law region
• work done in stretching a material

  0.5kx2