# A nylon climbing rope and a cast iron rod are both subjected to increasing tensile forces until they fail. The nylon rope stretches considerably before breaking, whilst the cast iron rod snaps with very little extension. Explain the difference in behaviour of these two materials in terms of their mechanical properties.

> AQA A-Level Physics (7408) — 3.4.2 Materials · Explain · 5 marks

## Mark scheme (5 marks)

1. The nylon rope is described as ductile (or malleable / not brittle)
2. The nylon rope undergoes a large (plastic) deformation before breaking / it does not return to its original length
3. The cast iron rod is described as brittle
4. A brittle material breaks / fractures with little or no plastic deformation (snaps suddenly without stretching significantly)
5. The cast iron has a higher stiffness (than nylon) / a greater force is needed to produce the same extension

## Related

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