During a spring experiment, a student notices that after a certain load the plotted force‑extension points start to curve away from the straight line. What does this indicate about the spring’s behaviour and why should the spring not be overloaded beyond this point?

The curvature indicates the spring has exceeded its limit of proportionality and is no longer obeying Hooke’s law; it is entering the elastic limit. Beyond this point the spring may undergo inelastic deformation or permanent damage. Overloading it can cause permanent change in length or breakage, so it should not be used beyond this load.

The answer demonstrates understanding of the limit of proportionality, the transition to non‑linear behaviour, and the practical safety implications of overloading a spring. It tests conceptual knowledge of elastic vs inelastic deformation.