AP Physics 1 Unit 4 Podcast

What's in this episode

• 0:00 – Intro — Why momentum is the perfect tool for collisions
• 2:00 – Linear momentum (4.1) — p = mv, the vector that everyone forgets is a vector
• 5:00 – Change in momentum and impulse (4.2) — J = FΔt = Δp
• 9:00 – Newton's 2nd law in momentum form — F = Δp/Δt, the truly general statement
• 12:00 – F-t graphs and p-t graphs — Area gives impulse; slope gives force
• 15:00 – Conservation of momentum (4.3) — Why total p is the same before and after
• 19:00 – Recoils and explosions — Rifles, cannons, and ice skaters pushing off
• 22:00 – Elastic vs. inelastic collisions (4.4) — When KE is conserved and when it isn't
• 26:00 – Perfectly inelastic collisions — The "they stick together" classic problem
• 29:00 – Wrap-up — The 3 big ideas in one minute

How to use the podcast

First listen: Play at 1× speed with no distractions. Don't try to take notes — just absorb why momentum is conserved and when KE is too.

Second listen: Speed up to 1.25× or 1.5× and follow along with the Cheat Sheet or Essentials page open. Pause when you hit a collision-type distinction you're shaky on.

Right before the exam: Play at 1.5–2× as background while reviewing flashcards. Unit 4 is mostly about a few key equations and one big principle — repetition makes them automatic.