Energy stored in a spring

• Elastic potential energy


  The energy stored in when an object is stretched or compressed

  
• Work done on a spring

  Equal to the amount of elastic potential energy stored in a spring when it is elastically stretched

  
• Elastic stretch


  When an object returns to it original shape when the stretching force is removed

  
• Inelastic (plastic) stretch


  When an object does not return to it original shape when the stretching force is removed

  
• E = 1/2 kx²

  The equation linking elastic potential energy, spring constant and extension (or compression)

  
• E


  The symbol for elastic potential energy

  
• k


  The symbol for spring constant

  
• x


  The symbol for extension (or compression)

  
• Joules (J)


  The SI unit for energy

  
• Newtons per metre (N/m)

  The SI unit for spring constant
• Metres (m)


  The SI unit for extension

  
• Force-extension graph


  A graph of force against extension for an object being stretched

  
• Significance of the gradient of a force-extension graph

  Equal to the spring constant of the object being stretched when it is stretching elastically

  
• Significance of the area under a force-extension graph

  Equal to the work done or the elastic potential energy stored by the object being stretched

  
• Linear extension (on a force-extension graph)

  Occurs below the limit of proportionality when the object is deforming elastically

  
• Limit of proportionality (on a force-extension graph)

  The point at which the extension of the object changes from a linear to a non-linear extension

  
• Non-linear extension (on a force-extension graph)

  Occurs above the limit of proportionality when the object is deforming inelastically