This exam tips covers Exam Tips — Impulse and Collisions within Impulse & Collisions for GCSE Physics. Revise Impulse & Collisions in Forces for GCSE Physics with 13 exam-style questions and 10 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 5 of 7 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
💡 Exam Tips — Impulse and Collisions
🎯 Common Question Types:
- Calculate impulse from force and time (2 marks)
- Calculate average force during a collision (2-3 marks)
- Explain how crumple zones / airbags reduce force (3 marks)
- Distinguish elastic from inelastic collision (2 marks)
- Interpret area under a force-time graph (2 marks)
📝 Key Command Words:
- Calculate: Show impulse = F × t = Δp; include units (N s or kg m/s)
- Explain: Use "increasing time → decreasing force" chain of reasoning
- Suggest: Apply the physics principle to an unfamiliar context
- State: "Momentum is always conserved; kinetic energy is only conserved in elastic collisions"
⚠️ Common Mistakes to Avoid:
- Confusing impulse (N s) and momentum (kg m/s) — they are numerically equal but described differently
- Forgetting to include direction in momentum change calculations
- Saying kinetic energy is conserved in all collisions — it is ONLY conserved in elastic collisions
- Misreading force-time graphs — area = impulse, NOT force or velocity
Practice questions for Impulse & Collisions
Which equation correctly defines impulse?
Explain how an airbag reduces the risk of injury to a driver in a collision.
Quick recall flashcards
Understanding Impulse
Impulse = Force × time (F × t) — measured in N s
Understanding Impulse
Impulse = Change in momentum (Δp = mΔv) — measured in kg m/s