In stretching a spring in an experiment, a student inadvertently stretches it past its elastic limit; the

Question:

In stretching a spring in an experiment, a student inadvertently stretches it past its elastic limit; the force-versus-stretch graph is shown in Fig. 5.30. Basically, after it reaches its limit, the spring begins to behave as if it were considerably stiffer. How much work was done on the spring? Assume that on the force axis, the tick marks are every 10 N, and on the x-axis, they are every 10 cm or 0.10 m.