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LearnCambridge97022025–2027Paper 1 · Multiple ChoiceDeformation of solids
Paper 1 · Module

Deformation of solids

2 subtopics≈ 65 min in total
Start the module: Stress, strain and the Young modulusOpen graphing calculator

  1. Stress, strain and the Young modulus

    A spring or wire obeys Hooke's law, F=kxF=kx, up to its limit of proportionality. To compare materials rather than particular objects, use stress (σ=FA\sigma=\tfrac FA) and strain (ε=xL\varepsilon=\tfrac xL). Their ratio in the linear region is the Young modulus, E=σεE=\dfrac\sigma\varepsilon, a property of the material alone.

    ≈ 35 min

  2. Elastic and plastic behaviour

    Below its elastic limit, a material returns to its original shape when the load is removed; beyond it, it's permanently (plastically) deformed. The work done stretching a material is the area under its force–extension graph, and within the limit of proportionality the stored elastic potential energy is EP=12Fx=12kx2E_P=\tfrac12Fx=\tfrac12kx^2. Ductile materials deform plastically a lot before breaking; brittle ones snap.

    ≈ 30 min