Momentum is conserved in every collision. The coefficient of restitution then supplies the second equation you need to find both velocities afterwards.
Syllabus points covered
- Use conservation of linear momentum for direct and oblique impacts
- Use Newton's experimental law and the coefficient of restitution
- Solve problems involving impacts between two particles and impacts with a fixed surface
- Calculate the loss of kinetic energy in an impact
Common mistakes
- Not assigning a consistent positive direction before writing the momentum equation.
- Getting the restitution equation the wrong way round — separation speed over approach speed.
- Assuming kinetic energy is conserved when e < 1.
- In oblique impacts, forgetting that the component parallel to the surface is unchanged.
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
Looking for whole papers by session? All Further Mathematics past papers