Momentum & Collisions Explained — p = mv, Conservation & the Newton Cradle Trick | Neon Chalk

Momentum and collisions: p = mv is a vector (signs matter), and in an isolated system the total momentum before any collision equals the total after: m1u1 + m2u2 = m1v1 + m2v2. We run two worked examples: a 2 kg cart at 3 m/s hits a stationary 1 kg cart and they stick (→ v = 2 m/s, with the 3 J of lost kinetic energy tracked), and the elastic equal-mass bounce derived from momentum plus energy conservation (the incoming ball stops dead, the target leaves at u — the Newton cradle trick). Traps covered: momentum direction signs, external impulse from friction breaking conservation, and the elastic / inelastic / perfectly-inelastic split. Chapters: 0:00 — Momentum & collisions: the account book of every impact 0:09 — p = mv: what momentum is 0:20 — Mass vs speed: the trade 0:36 — Trap zero: momentum is a vector 0:54 — Conservation in isolated systems: m1u1 + m2u2 = m1v1 + m2v2 1:17 — Why it works: Newton's third law 1:33 — Three collision types: elastic, inelastic, perfectly inelastic 1:54 — Example 1 setup: 2 kg cart hits a 1 kg cart, they stick 2:06 — Example 1: v = 2 m/s (momentum conserved) 2:30 — The energy check: 9 J to 6 J 2:51 — Example 2 setup: elastic pool balls 3:06 — The derivation: u = v1+v2, u² = v1²+v2² 3:41 — Result: incoming stops dead, target leaves at u 4:05 — Trap: signs cancel — head-on clay balls 4:31 — Recap 4:58 — Next: Circular Motion & Centripetal Force Neon Chalk is short, no-fluff maths and physics — every step drawn out as it's explained. Subscribe for the next topic.