Required practical 6: stretching a spring

• Investigating the relationship between force and extension for a spring

  1. Set up clamp stand, bosses, and clamps

  2. Place heavy weight on clamp stand

  3. Attach meter rule under spring, with top at 0 point

  4. Attach wooden splint pointer to bottom of spring, keep horizontal

  5. Read unstretched length of spring

  6. Add 1 Newton weight, read new pointer position

  7. Continue adding 1 Newton weights, read pointer positions

  8. Calculate extension for each weight by subtracting unstretched length

  9. Plot extension vs weight graph
• Graph of extension vs weight

  • Straight line through origin
  • Linear relationship between force and extension
  • Elastic deformation - extension returns to 0 when weight removed
  • Inelastic deformation - over-stretching, extension remains when weight removed
• Linear relationship


  Straight line graph, extension directly proportional to weight
• Nonlinear relationship


  Curved graph, extension not directly proportional to weight
• Elastic deformation


  Extension returns to 0 when weight removed
• Inelastic deformation


  Extension remains when weight removed, spring over-stretched
• Limit of proportionality


  Point on graph where relationship becomes nonlinear
• Spring constant is the same for any part of the graph as long as the limit of proportionality is not exceeded