1.1.5 Elastic Potential Energy

• Elastic potential energy (EPE)


  The energy stored in an object when it is stretched, compressed, or deformed, and has the potential to return to its original shape
• Elastic potential energy

  • Stored in elastic materials
  • Released when material returns to original shape
• Hooke’s Law


  The force required to stretch or compress a spring is directly proportional to the extension or compression, as long as the material’s elastic limit is not exceeded
• F

  Force applied to the spring (in newtons, N)
• k

  Spring constant (in newtons per meter, N/m)
• x

  Extension or compression of the spring (in meters, m)
• E_e

  Elastic potential energy (measured in joules, J)
• Spring constant (k)

  A stiffer spring stores more energy for the same amount of stretch or compression
• Extension/Compression (x)


  The more you stretch or compress the spring, the more energy is stored; energy increases with the square of the extension or compression
• Elastic potential energy is measured in joules (J)
• Examples of elastic potential energy

  • A stretched rubber band
  • A compressed spring in a toy
  • An archery bow
• When you stretch a rubber band

  You store elastic potential energy in it
• When you compress a spring in a toy

  Elastic potential energy is stored in the spring
• When you draw back an archery bow

  Elastic potential energy is stored in the bowstring
• The elastic potential energy stored in the spring is 1 joule