Direction · impulse · conservation

Momentum

Momentum keeps direction in the accounting. Force acting over time changes momentum; internal interactions redistribute it while an isolated system preserves the total vector.

Unit throughline

Momentum is motion accounting that remembers which way the motion points.

We start with one object, learn how impulse changes its momentum, then widen the system to several interacting objects and finally compare collision types.

masshow much matter
velocityspeed + direction
momentumdirection preserved
mass × velocity → directional motion quantity → changed by impulse → conserved for isolated systems
Learning path

Follow momentum from one object into an interacting system.

Momentum
p = mv
Impulse
J = Δp
Conservation of Momentum
Σpbefore = Σpafter
Collisions
before ↔ after
Momentum is a vector

Reversing velocity reverses momentum even when mass and speed are unchanged.

Impulse changes momentum

A modest force acting longer can produce the same momentum change as a large force acting briefly.

System totals matter

During a collision, objects exchange momentum internally. The isolated system total is the quantity that stays fixed.