Elastics

• Deformation


  Change in the shape of an object, as a result of forces
• Elastic deformation

  Change in the shape of an object, which can be reversed so it will return to its original shape
• Inelastic deformation


  Change in the shape of an object which cannot be reversed so it won’t return to its original shape
• Minimum number of forces required to stretch, compress, or bend an object

  2
• Spring constant


  How many newtons of force needed to stretch or compress the object by 1 metre
• High spring constant


  Spring is more firm
• Low spring constant


  Less firm
• Hooke’s Law


  Extension of an object is directly proportional to the force applied
• Elastic limit 


  Point at which an object being stretched stops deforming elastically and starts deforming inelastically
• Point where extension is no longer proportional to force applied

  Limit of proportionality
• Elastic potential energy


  Energy stored in an object when its stretched or squashed
• When discussing elastic potential energy, what does extension mean?


  How much longer or shorter the object is due to being stretched or squashed
• Unit for extension


  Metres (m)