Why a Small Tilt Can Finish the Job
A bowling pin stands upright because its base supports it beneath its center of mass—the point where its weight effectively acts. As the pin tips, that balance shifts. Once the center of mass moves beyond the edge of the supporting base, gravity no longer pulls the pin back upright. Instead, its weight creates a turning force, or torque, that carries it farther over.
That is the significance of the roughly seven-degree tipping point: the pin does not need a dramatic shove after it has crossed the point where it can balance. Gravity supplies the continuing force, and the pin accelerates toward the floor.
The Ball Starts a Chain Reaction
A ball hit does not need to strike every pin squarely. It gives one pin a sudden push; that pin can then topple into its neighbors, transferring motion through the rack. A glancing collision may be enough to tilt a pin past its balance point, after which gravity takes over.
The exact motion can include sliding, spinning, and further bumps, so seven degrees is not a magic angle that guarantees a fall in every collision. But it explains why a seemingly slight deflection can matter: the crucial change is not how far the pin has moved, but whether its weight has shifted beyond the base that was holding it up.
