Elastic strings and springs exert a force proportional to their extension. Because that force varies, energy methods are usually easier than force methods.
Syllabus points covered
- Use Hooke's law in the form T = λx/l
- Understand and use the concept of elastic potential energy
- Solve problems involving elastic strings and springs, including equilibrium and motion
- Use conservation of energy in problems involving elastic elements
Common mistakes
- Using the natural length instead of the extension in Hooke's law.
- Forgetting that a string can only pull, never push, so it goes slack rather than compressing.
- Omitting elastic potential energy from a conservation of energy statement.
- Confusing the modulus of elasticity with the stiffness constant.
Worksheets
Use these as soon as you've learned the topic and need to practise it. Start with the worksheet, check yourself against the answers, and only then look at the step-by-step solutions.
- Practice worksheetComing soon
- Worksheet answersComing soon
- Step-by-step solutionsComing soon
Topical past papers
Move on to these once you've worked through the worksheets and are ready for harder, exam-style questions. Real past-paper questions on this topic, with the official mark scheme and full worked solutions.
- Topical questions
- Mark scheme
- Step-by-step worked solutionsComing soon
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