1.29 describe experiments to investigate how extension varies with applied force for helical springs, metal wires and rubber bands

The most common experiment for this goes like so:

• Attach a spring to a newton meter and measure its length
• Add a 50g weight and measure again
• continue to add another weight and take another measurement
• Do this up to 400g

by plotting a graph from the results from this you can see the extension increases with force; as each time a weight is added the spring gets longer.