IB DP Physics (2025) A2.8 Collisions & Explosions

B DP Physics lesson pack on collisions and explosions, Topic A.2 Forces and momentum, SL and HL, first assessment 2025: conservation of momentum, proved by the class from Newton’s laws, then applied to every collision and explosion. Editable worksheet, 59-slide lesson deck, teacher key, worked solutions and a questions-only assessment, supplied as self-contained HTML plus colour and black-and-white PDF.

What students learn

• Conservation of momentum in an isolated system, derived from Newton’s second and third laws.
• One method for every one-dimensional collision and explosion.
• Elastic and inelastic collisions and explosions, told apart by the change in kinetic energy.
• HL: two-dimensional collisions, with momentum conserved along two perpendicular axes.

IB skills (Tool 3: Mathematics, with Inquiry 2: Collecting and processing data):

• Add and subtract vectors (practised).
• Resolve vectors into perpendicular components (practised, HL only).
• Use arithmetic and algebra to solve problems (practised).
• Linearize graphs, only where appropriate (practised).
• Interpret the gradient and intercept of a graph (practised).
• Draw lines of best fit (practised).
• Identify and justify the removal of outliers (practised).

What’s included:

• Student Worksheet - 24 pages
• Teacher Key - 39 pages
• Worked Solutions - 25 pages
• Assessment - 19 pages
• Lesson deck - 59 slides

At HL, nine structured questions and five multiple-choice items worth 91 marks; SL drops two questions and one item, leaving 76. Sixteen figures, four with answer layers stripped from the student copy, not hidden. Four questions, 39 marks, are worked in the room and one item is the exit ticket; the rest go home, including a data question that recovers a trolley’s mass from a linearized graph.

One pack serves a mixed class: the HL material is marked on the student’s copy and set as homework, so HL needs no extra class time.

A Nature of Science note covers what measurements can and cannot prove. Kinetic energy is not taught until Topic A.3, so Ek = ½mv² comes from the data booklet and is used only to compare totals. Worksheet and deck open in any modern browser with nothing to install, and the worksheet is fully editable. SI units, IB notation and IB command terms throughout. Suitable for grades 11-12 (ages 16-19) as a lesson, cover lesson, homework or revision.

Related resources:

• Momentum, Impulse and F = Δp/Δt, the lesson before this one
• Topic A.2 Test: Forces and Momentum, the topic test
• Resolving Vectors, the skill pack behind the HL work
• Unit Conversion, including km h⁻¹ into m s⁻¹ (free)

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