Score: 0
Contract 1: First Rack Sink it! Balls: 3
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About Momentum Billiards

Set the cue ball's velocity vector, watch momentum arrows survive every collision and fulfill pool-table contracts in this free online conservation of momentum game about elastic and inelastic collisions.

Momentum Billiards is a free online conservation of momentum game where every pool shot is a physics problem. Each rack arrives as a contract (sink a named ball, at a minimum speed, sometimes through a required cushion or a required merge) and you answer by setting the cue ball's velocity vector. Pull back, release and watch ghosted p = mv arrows show momentum before and after every collision.

Every mechanic maps onto a real equation from classical mechanics. Head-on equal-mass collisions are elastic: the cue ball stops and hands its momentum p = mv to the target, so the target leaves with nearly the full incoming speed. Angled shots split momentum into perpendicular components that still sum to the same total vector. Cushion bounces deliver an impulse J = Δp that reverses only the perpendicular component, which is why bank shots keep their angle but bleed speed. Sticky putty collisions are perfectly inelastic: the merged masses share the total momentum, v drops, and the kinetic energy meter falls, the cleanest possible demonstration that momentum is conserved while KE is not.

Newton himself treated collisions through his third law, and the cradle finale replays his insight: equal-mass elastic collisions pass momentum down a chain almost untouched, so the far ball ejects with the incoming momentum. The same accounting governs billiards, air-hockey pucks, car-crash forensics and particle-physics detectors where momentum vectors are reconstructed track by track.

Key Science Concepts

What You'll Learn

Grade Level: Middle School, High School

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How to play

  1. 1. Pull & Release Drag back from the cue ball to set its velocity vector. The dotted line and live v readout preview the strike.
  2. 2. Meet the Contract Each rack names a target ball and a minimum pocket-entry speed. Sink it fast enough before your balls run out.
  3. 3. Read the Arrows Every ball carries a p = mv arrow. Ghosted arrows mark momentum before and after each collision: the totals always match.
  4. 4. Bank the Cushion Some clauses require a rail bounce. The cushion flips the perpendicular component; the parallel one survives.
  5. 5. Merge the Putty Sticky collisions merge masses and share momentum: v drops, momentum holds and kinetic energy visibly falls.
  6. 6. Run the Cradle The finale is a Newton's cradle: momentum passes through the line and ejects the far ball. Predict the outgoing configuration.

Frequently asked questions

Is Momentum Billiards free to play?
Yes. Momentum Billiards is completely free to play in your browser. There is no download, install or account needed.
What grade level is Momentum Billiards for?
Momentum Billiards is designed for Middle School, High School students and works well as a classroom activity or homework.
Does Momentum Billiards work on phones and tablets?
Yes. Momentum Billiards runs in any modern browser on desktop computers, Chromebooks, tablets and phones in landscape mode.

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