🎱 **Billiards Physics!** A pool table with 6 pockets, a white cue ball, and 6 target balls in a triangle rack. **How to play:** 1. Press **▶ Play** to start 2. **Drag the white cue ball** — pull back to aim 3. **Release** to shoot! Power = how far you pull Sink balls into the 6 pockets. Watch: - Balls **bounce** off each other (elastic collision) - Balls **reflect** off the cushions (wall bounce) - Balls **slow down** from table friction - Balls **disappear** into pockets Ask me anything about the physics!

Billiards Physics

Hit balls into pockets — learn elastic collision and momentum

Billiards is physics in action. When the cue ball strikes another ball, momentum and kinetic energy transfer through the collision. A head-on hit transfers nearly all speed to the target ball. An angled hit splits the momentum — the two balls fly off at right angles.

Key physics:

  • Elastic collision: kinetic energy is (mostly) conserved — balls don't deform
  • Momentum conservation: m_1 v_1 + m_2 v_2 = m_1 v_1' + m_2 v_2'
  • Rolling friction: the felt slows balls down over time
  • Wall bounce: cushions reflect the velocity component perpendicular to the wall

Press ▶ Play, then drag the white cue ball to aim — pull back and release to shoot. Ask the AI to add more balls or explain why the balls separate at 90° after a glancing collision.

Related Topics

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Why do pool balls separate at 90° after a collision?
When two equal-mass balls collide and one is stationary, momentum conservation requires their final velocities to be perpendicular — they fly off at exactly 90° to each other. This is because kinetic energy conservation plus momentum conservation constrains the angle to 90° in the equal-mass case.
What is an elastic collision?
An elastic collision conserves both momentum AND kinetic energy. Pool balls approximate this well because they are hard and don't deform much. In a perfectly elastic head-on collision between equal masses, the first ball stops completely and the second takes all its speed.
How does rolling friction work on a pool table?
The felt surface creates friction that decelerates the ball. In this simulator, each frame the horizontal velocity is multiplied by a friction coefficient (0.995 for felt). This gradually slows the ball until it stops — just like a real table.
How do cushion bounces work?
When a ball hits a cushion (wall), the velocity component perpendicular to the wall is reversed with some energy loss (restitution ~0.85). The parallel component continues unchanged. This is why you can bank shots off the rails at predictable angles.
Why is this a good way to learn physics?
Billiards is one of the purest examples of Newtonian mechanics. Every shot demonstrates momentum conservation, energy transfer, friction, and reflection. The 3D simulator lets you see these principles in action and experiment with different shots.