Elastic vs Inelastic Collisions: Why the Cue Ball Stops Dead | Physics Explained 8.3

Why does a cue ball stop dead, while lumps of clay stick together? This lesson sorts collisions into elastic, inelastic and perfectly inelastic using kinetic energy (½mv²), and shows that momentum is conserved in all of them. Worked examples: a goalie catching a puck (7.5 cm/s recoil, over 99% of the kinetic energy lost), two steel carts bouncing apart (1.56 m/s, almost no energy lost), why equal masses swap velocities (and a real Newton's cradle in 3D: one in, one out; two in, two out), and a two-dimensional collision solved with x and y components (0.886 m/s at 48.5° below the axis). Chapters: 0:00 Intro 0:50 Bounce or stick? 2:34 Solving collisions in 1-D 3:12 Worked example: the goalie and the puck 4:32 Worked example: two steel carts 5:52 Why the cue ball stops dead 6:50 A real Newton's cradle 7:36 Collisions in two dimensions 8:34 Worked example: the dark room 10:34 Common mistakes 11:11 Recap 11:52 Check yourself 13:17 Up next Physics Explained, Chapter 8: Momentum (lesson 3 of 3) Adapted from Physics by OpenStax (https://openstax.org/details/books/ph..., licensed under CC BY 4.0 (https://creativecommons.org/licenses/.... The animations and narration are original to Prime Mover. OpenStax is not affiliated with this channel and does not endorse it. Prime Mover: learn it, build it, share it.