Physics Year 11 - Module 2 - Lesson 12
Conservation of Momentum
1. Key Ideas
Before a gun fires, the total momentum of the gun-bullet system is zero. After — the bullet races forward and the gun kicks back. Add them together: still zero. Momentum was conserved.
- Law of conservation of momentum
- Why Newton's Third Law leads to conservation
2. Success Criteria
By the end, you should be able to:
- Law of conservation of momentum
- Condition: closed system, no net external force
- Elastic, inelastic, perfectly inelastic definitions
3. Key Terms
4. Activity: Build the Lesson Map
Use the lesson to complete the table. Keep answers brief but specific.
| Prompt | Your answer |
|---|---|
| Main concept | |
| Important example | |
| Common mistake to avoid | |
| How this links to the next lesson |
5. Short Answer Questions
1. Explain this lesson goal in your own words: "Law of conservation of momentum". Use one specific example from the lesson.
2. Apply this idea to a new example: "Condition: closed system, no net external force". Show your reasoning clearly.
3. Analyse why this idea matters for understanding Conservation of Momentum: "Elastic, inelastic, perfectly inelastic definitions".
6. Extend: Apply the Idea
A student gives a memorised answer about Conservation of Momentum but does not use evidence or reasoning.
Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.
7. Multiple Choice
1. What is the best first step when answering a question about Conservation of Momentum?
A. Identify the key concept being tested
B. Write every fact from memory
C. Ignore the command word
D. Skip examples and evidence
2. Which answer would show stronger understanding of Conservation of Momentum?
A. An answer with accurate terms and reasoning
B. A copied definition only
C. A single-word response
D. An answer with no example
3. What should you do if a question asks you to explain?
A. Link the idea to a reason or cause
B. List unrelated facts
C. Only draw a diagram
D. Write the shortest possible answer
8. Success Criteria Proof
Finish with evidence that you can do each success criterion.