Collisions, Explosions and Impulse
Analyse one-dimensional interactions through momentum, kinetic energy, equal-and-opposite forces and impulse.
How to study Higher Physics
Move between physical models, relationships, units, graphs and justified conclusions, while using current official materials for exact paper and assignment conditions.
Core concepts
Concept 1
momentum conservation
Exam cue: Choose a positive direction before assigning velocity signs.
Concept 2
elastic, inelastic and explosive energy changes
Exam cue: Conserve total momentum for an isolated system.
Concept 3
Newton’s third law
Exam cue: Use force–time area as impulse and change in momentum.
Concept 4
impulse and force–time graphs
Risk pitfalls and guardrails
Conserving kinetic energy in every collision.
Guardrail: Check assumptions, prefixes, units, significant figures and whether the statement is supported by evidence.
Dropping direction signs from momentum.
Guardrail: Choose a positive direction and preserve signs through the calculation before interpreting the result.
Comparing third-law forces acting on the same object.
Guardrail: Check assumptions, prefixes, units, significant figures and whether the statement is supported by evidence.
Memory anchors
Momentum
p = mv; momentum is a vector.
Momentum conservation
Total momentum before equals total momentum after for an isolated system.
Elastic collision
Both total momentum and total kinetic energy are conserved.
Inelastic collision
Momentum is conserved but total kinetic energy decreases.
Impulse
Impulse equals FΔt for an average force and equals change in momentum.
Force–time area
The signed area under the graph is impulse.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
A 3.0 kg trolley moves east at 4.0 m s⁻¹. What is its momentum eastward?
Taking right as positive, a 0.50 kg ball moves left at 8.0 m s⁻¹. What is its momentum?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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