The ball follows projectile motion with gravity, air drag, and a Magnus/seam sideways force before pitching. After the bounce, seam and spin cause additional lateral deviation ("seam movement" / "turn") before reaching the batsman.
F_magnus = k·v×ω (sideways swing force)
y(t) = y0 + v_y0·t − ½g·t²
Post-bounce deviation ∝ spin · (1 − restitution loss)
- Ball speed — initial release velocity down the pitch; faster balls reach the bat sooner.
- Swing (Magnus) — sideways curve in flight before the bounce, from seam orientation and airflow.
- Length — where along the pitch the ball bounces (short/good-length/full).
- Spin deviation — extra sideways kick applied at the bounce, simulating finger/wrist spin "turn".
Real-world application: this swing + seam + spin model is exactly what fast bowlers and spinners exploit to deceive batsmen, and what ball-tracking systems like Hawk-Eye reconstruct for umpiring decisions.