PHYS 4A - Lecture 13 - Impulse and Momentum, ver. 2

Lecture 13 (of ~30) — Physics 4A in 30 Lectures introduces momentum as the second major conservation-law tool (alongside energy) and shows why energy conservation alone isn’t enough to predict what actually happens in many interactions—especially collisions. We begin by defining momentum as a vector quantity and building intuition for what it captures about motion. Next we introduce impulse and the impulse–momentum theorem, connecting forces that act over time (including large forces over short times) to changes in momentum. From there we lay out the conditions for conservation of momentum (system choice + negligible external impulse) and how momentum conservation often pairs with energy ideas to classify collisions (what can be predicted from momentum alone vs. what needs additional information). The lecture closes with simulation-based intuition building, including an impulse/momentum simulation and a PhET collision lab demonstration that connects the theory to Newton’s-cradle-style behavior. Chapters 00:00:00 – Lecture 13 Intro 00:01:43 – Definition of Momentum 00:14:40 – Impulse, Change of Momentum and Force 00:41:42 – Conservation of Momentum (& Energy) 01:07:51 – Impulse and Momentum Simulation 01:15:23 – Simulating Newton’s Cradle with PhET Collision Lab