A rubber exercise band is stretched by a person during a workout. At first, the band stretches easily and returns to its original length when released. The person then pulls the band much harder until it no longer returns to its original shape. Explain what happens to the band during both stages of stretching.

Edexcel GCSE Physics (1PH0) — 15.1 Forces and matter (Phys only) · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

In the first stage the band undergoes elastic distortion – the applied force is below the elastic limit, so the band returns to its original shape when the force is removed.
In the second stage the elastic limit is exceeded – the applied force goes beyond the elastic limit, causing plastic distortion, so the band does not return to its original shape when the force is removed.

Examiner tips

  • Use the terms "elastic distortion" and "elastic limit" for the first stage; "plastic distortion" and "elastic limit exceeded" for the second stage.
  • Show the cause–effect relationship: force below limit → elastic; force above limit → plastic.
  • Keep the answer concise – one sentence per stage.
  • Use UK spelling (distortion).

Common mistakes

  • Confusing elastic with plastic deformation; writing that the band still returns to its original shape in the second stage.
  • Using vague terms like "stretching" or "bending" instead of the specific deformation types.

Mark scheme (4 marks)

  1. In the first stage, the band undergoes elastic distortion / elastic deformation
  2. In the first stage, the band returns to its original shape / length because the force is below the elastic limit
  3. In the second stage, the elastic limit has been exceeded / the force applied goes beyond the elastic limit
  4. In the second stage, the band undergoes plastic distortion / plastic deformation, so it does not return to its original shape when the deforming force is removed

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