What is momentum?

Momentum: p = m × v. Momentum is how much 'oomph' a moving thing carries: its mass times its velocity. When things collide or push apart, momentum passes from one to the other, but the total never changes. Momentum is mass times velocity, p = m v, in kg·m/s, and it has a direction.

Read how it works: What is momentum? · The history of momentum · More boxes on Glassbox

Chapters in this interactive model

1. Momentum: mass on the move: Crash two carts together, stick them, or spring them apart. The total momentum never changes.
2. Crashes, crumple zones and catches: Momentum sets who moves where after a crash. Stretching the stop sets how much it hurts.
3. Push-offs, recoil and rockets: Push two things apart and their momenta cancel. Keep throwing mass back and you get thrust.
4. Cradles, carrom and cricket: Momentum passes down a row of steel balls, splits at an angle on a carrom board, and flies off a bat.
5. Myths, spin and the push of light: Who really “wins” a crash, why momentum isn’t energy, spinning momentum, and sunlight that pushes.