A-Level Further Maths · Further Mechanics
Elastic Collisions
What is it
An elastic collision is one where both momentum and kinetic energy are conserved — unlike general collisions, where only momentum is guaranteed to be conserved, elastic collisions allow the use of an extra equation (Newton's law of restitution or energy conservation) to fully solve for the resulting velocities.
Why it matters
Elastic collision problems test genuinely deep mechanical reasoning by combining two conservation principles at once, and they connect directly to real physics contexts like particle collisions and billiard ball dynamics.
Exam tip
Set up both the momentum conservation equation and the restitution equation (or energy conservation) before attempting to solve — trying to solve with momentum alone leaves the system under-determined, since a general collision needs both equations.
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