LuduminaFM-14 · FM-U5 · Planned
Momentum and closed-system collisions
Learning objectives
Calculate momentum; explain conservation when external resultant is negligible; P-H: calculate collision outcomes.
8463 §§4.5.7.1–4.5.7.2 / 8464 §§6.5.5.1–6.5.5.2
DfE single-science pp.35–37 / Combined pp.30–32. Evidence checked 30 September–1 October 2026. Skills: WS1.2,3.5; MS3b,3c.
Explanation
Momentum uses signed velocity and is conserved when external resultant force is negligible during the event. Kinetic energy need not be conserved in an inelastic collision. Separate Higher adds collision-outcome calculations beyond the shared conservation explanation.
Concepts, equations and units: p=mv; kg m/s; signed total momentum conserved for closed system. Collision-outcome calculations P-H only.
Prediction, demonstration and game exercise
Predict, observe, explain
Compare carts before and after a collision; separately track KE to show it need not be conserved.
Planned learner game exercise
Choose masses and velocities, predict direction and conserved total; P-H solve coupled-cart final speed.
Independent practice
C-H calculate individual momenta and explain conservation; P-H two event calculations.
Original practice example · Shared Higher
A 2 kg cart travels right at 3 m/s. Find momentum.
Show working and model answer
Working / reasoning
Choose right positive: p = mv = 2 × 3.
Answer
6 kg m/s to the right.
Exit check and success criteria
Correct signed momenta and conservation explanation; P-H correct final speed with stated closed-system assumption.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Momentum equals energy; conservation requires equal masses; all collisions conserve KE.
Practical preparation
Optional trolley collision measurements, AT1,2,3.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.