🔮 2D Double Pendulum

Real coupled Lagrangian equations of motion, integrated with RK4. Drag the bobs to set the starting angles, then enable Twin mode to launch a second pendulum offset by a fraction of a degree and watch the two paths diverge exponentially — the hallmark of deterministic chaos.

Pendulum

Length L1 (m) 1.0 Length L2 (m) 1.0 Mass m1 (kg) 1.0 Mass m2 (kg) 1.0

Initial angles

theta1 (deg) 120 theta2 (deg) -30

Or drag the bobs directly on the canvas.

Dynamics

Gravity g (m/s2) 9.81 Damping 0.000 Speed 2 Trail length 600

Chaos twin

Adds a second pendulum offset by 0.01° to show sensitivity to initial conditions.

theta1—

theta2—

omega1—

omega2—

Energy E—

Divergence—

Damping=0 conserves energy; tip is sensitively dependent on initial angles.