Investigating Springs

• You Can Investigate the Link Between Force and Extension


  1. Before you start, set up the apparatus as shown in the diagram

  2. Measure the mass of each of your masses (with a mass balance) and calculate its weight (the force applied) using W= mg (p 88)

  3. Do a quick pilot experiment to check your masses are an appropriate size for your investigation

  4. Measure the natural length of the spring (when no load is applied) with a millimetre ruler clamped to the stand

  5. Add a mass to the spring and allow the spring to come to rest. Record the mass and measure the new length of the spring. The extension is the change in length

  6. Repeat this process until you have enough measurements (no fewer than 6)
• You Can Plot Your Results on a Force-Extension Graph

  1. Plot a force-extension graph of your results

  2. If the line of best fit is a straight line, it means there is a linear relationship between force and extension (they're directly proportional)

  3. The gradient of the straight line is equal to k, the spring constant

  4. When the line begins to bend, the relationship is now non-linear between force and extension-the spring stretches more for each unit increase in force
• You Can Work Out Energy Stored for Linear Relationships

  1. As long as a spring is not stretched past its limit of proportionality, work done in stretching (or compressing) a spring can be found using: E = ½ ke²

  2. For elastic deformation, this formula can be used to calculate the energy stored in a spring's elastic potential energy store

  3. The energy in the elastic potential energy store of a stretched spring is equal to the area under a force-extension graph up to that point