A student was given a box of identical springs and asked to analyse them so that they could be used as newton meters.
The student performed an experiment, using the apparatus shown in the diagram, on one of the springs.
In the experiment the student measured the increase in length of the spring caused by a number of weights. The spring was tested to destruction (that is weights were added until the spring was damaged).
A graph of extension versus force was plotted as shown.
Study this graph carefully.
The spring obeys Hooke’s law for the earlier extensions and then when the spring becomes damaged it does not appear to do so.

Estimate, from your graph, the weight after the addition of which the law seems no longer to apply.