Newton's Cradle
No walls, no bounces off boundaries — just pendulums, gravity, and momentum passed
cleanly from one ball straight through to the other end. Click a ball to pull it back
yourself.
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Sound: On
How it works: each ball hangs from a fixed pivot on a rigid string
of the same length, so it swings like a pendulum — its angle accelerates toward
center under gravity exactly like a real pendulum's restoring force. Balls at rest
hang flush against their neighbors. When a swinging ball's edge reaches a resting
neighbor, we resolve it as a perfectly elastic, equal-mass collision, which has a
clean physical property: the moving ball stops dead and the ball it hit inherits its
exact velocity. Chain that through several touching balls and the momentum passes
straight through the stationary middle balls (which barely move) to launch only the
ball on the far end — the classic click-clack. Drag any ball out to the side yourself
to inject your own swing.