Momentum
The product of mass and velocity: p = mv, measured in kg·m·s⁻¹. A vector quantity (has direction). The rate of change of momentum equals the net force: F = Δp/Δt (Newton's second law in momentum form). In isolated systems, total momentum is conserved (conservation of momentum).
Formula
p = mv
Real World
In a snooker match, a light cue ball (0.16 kg) travelling at 5 m/s transfers its momentum to the stationary red ball on impact — illustrating conservation of momentum in an almost perfectly elastic collision.
Exam Focus
In collision calculations, assign a positive direction first and keep signs consistent; losing track of direction is the most common error.
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