Learn the movement.
In the ideal equal-mass collision, the object ball leaves along the line joining the centers at contact. The remaining cue-ball velocity lies along the tangent, perpendicular to that line. The incoming cue line and the tangent are different lines.
The simple construction neglects throw, energy loss, unequal balls, and cloth effects. Stun excludes top and bottom spin at contact; it can coexist with sidespin, although this introductory scene deliberately leaves sidespin out.
One useful set.
- Setup & action
- Watch the collision freeze frame, predict a cue-ball zone, then compare the illustrated departure.
- What to watch
- Which line is the object-ball direction, and which is the tangent?
- Practice format
- 10 attempts is a starting suggestion. Record the pattern, not just the best one.
A common complication.
Drawing a ninety-degree angle from the incoming cue line instead of between the outgoing ball directions.
Change one thingFreeze at contact and identify the line of centers first.
What changes the result?
Distance, pace, contact point, spin at collision, balls, cloth, and execution can all matter. Keep the basic setup consistent before comparing one change. An exact-looking line is not evidence of an exact physical prediction.
A note to yourself.
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