England · Forces and motion · Unit FM-U5

Momentum

A proposed unit with 2 lectures, independent practice and a unit assessment.

Unit scope

Filters show lectures with relevant core content. Mixed lectures retain clearly labelled Higher/separate extensions; those extensions are not required on other routes. Difficulty is a design rating, not a GCSE grade.

Lectures

FM-U5 · Momentum

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FM-14 · FM-U5 · Planned

Momentum and closed-system collisions

  • ScopeShared Higher + Separate Physics Higher calculations
  • Difficulty3 / 4 · proposed
  • Time30–35 min · estimated
  • StatusPlanned

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.

Needs firstFM-07,FM-12

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.

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FM-15 · FM-U5 · Planned

Momentum change and protection

  • ScopeSeparate Physics Higher
  • Difficulty4 / 4 · proposed
  • Time30–35 min · estimated
  • StatusPlanned

Learning objectives

Calculate average force from momentum change; explain crumple zones, helmets and airbags.

8463 §§4.5.7.3 / No Trilogy counterpart

DfE single-science pp.35–37 / Combined pp.30–32. Evidence checked 30 September–1 October 2026. Skills: WS1.4,1.5,3.6; MS3b,3c.

Needs firstFM-14

Explanation

The same momentum change spread over a longer stopping time produces a smaller average force. This is why a buffer can reduce force without changing the cart’s initial momentum. Average force is distinct from peak force.

Concepts, equations and units: F_average=Δp/Δt=mΔv/Δt for fixed mass; N, kg, m/s, s; signed change.

Prediction, demonstration and game exercise

Predict, observe, explain

Stop equal-momentum carts with hard and padded barriers; compare impulse time traces.

Planned learner game exercise

Design a buffer with fixed stopping change; lengthen stopping time and inspect force.

Independent practice

Two average-force calculations and a causal protection explanation, including constraints.

Original practice example · Separate Physics Higher

A 2 kg cart slows from 5 m/s to rest in 0.50 s. Find average stopping-force magnitude.

Show working and model answer

Working / reasoning

Magnitude = mΔv/Δt = 2 × 5/0.50.

Answer

20 N opposite its initial motion.

Exit check and success criteria

Both calculations within rounding tolerance and explicit same Δp/longer time/smaller average force chain.

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

Padding reduces initial momentum automatically; the displayed force is necessarily peak force.

Practical preparation

Optional toy-cart/force-data analysis; no human impact trials.

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.

Full lecture page →

Area capstone

Sources and full programme

Sources checked 30 September–1 October 2026. Specifications govern content; textbooks supplement it. England has no single prescribed Physics course book. The full planning document includes sourced comparisons of Collins separate Physics and Trilogy books, Hodder/Hachette Physics and Oxford Physics listings, with access/approval limitations.

Download the complete Markdown programme and coverage matrix

A subsection map is proposed coverage. Clause-level educator review, item moderation, model validation and hands-on provision remain release gates. No all-board alignment or exam-board endorsement is claimed.