force and extension

• Investigating the relationship between force and extension for a spring

  1. Set up equipment (clamp stand, bosses, clamps, meter rule, spring, wooden splint pointer)

  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)
  • Slope gives spring constant
  • Elastic deformation - extension returns to 0 when weight removed
  • Inelastic deformation - permanent extension if over-stretched
• 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


  Permanent extension if over-stretched, exceeding limit of proportionality
• Spring constant


  Force required to produce unit extension, calculated from slope of linear graph
• The force equals the spring constant multiplied by the extension