How can one bowling ball knock down many pins?

A bowling ball rolls toward a group of standing pins. It may touch only a few of them, yet many can fall. The ball starts a chain of pushes that travels through the group.

When the ball hits a pin, it pushes the pin. The pin pushes back on the ball too. The ball’s motion changes, and the pin can slide, turn, or tip. The pin does not need to move in exactly the same direction as the ball.

A moving pin can hit another pin. That pin can then hit a third. Some pins fall because the ball reaches them, while others fall because another pin reaches them. The clatter comes from many separate touches.

A gap can interrupt the chain. A pin may miss its neighbor, or may reach it without enough motion to knock it over. That is why one rolling ball can produce very different results. A whole group can change because a push passes from object to object.