Equations · equation
Tip Offset and Spin
Billiards · 1835
- Equation
- ω = (5/2) v b / R² ; miscue beyond b ≈ R/2
- Field
- Billiards
- Year
- 1835
Symbols
ω spin imparted, radians per second · v cue-ball speed off the tip · b the tip's offset from the ball's centre, perpendicular to the cue · R ball radius
Significance
Hit off-centre and the impulse has a lever arm; the ball's moment of inertia is ⅖ mR², so the spin is 5/2 · v · b / R². Half a radius of offset — the practical limit before the tip slides off — gives a ball spinning about as fast as it would if it were already rolling at that speed. Above the centre it is follow, below it draw, to the side it is english (and squirt: the cue ball leaves a little off the cue's line, by an amount that is a property of the cue, not the table).
Referenced by
equation
skill
Open on the Equations shelf — the interactive card, the filters, and everything alongside it.