Planar Double Pendulum

Coupled equations of motion · RK4 fixed-step integrator · m₁ = m₂ = 1 kg · l₁ = l₂ = 1 m · g = 9.81 m/s²

running · t = 0.00 s

State

θ₁ (from down)	—
θ₂ (from down)	—
ω₁	—
ω₂	—
speed of bob 2	—
trail points	0

Energy check

E (undamped)	—
drift from E₀	—

No damping or driving: total energy should stay constant. Drift monitors the integrator.

Playback Speed 1.00× Trail length 900

Space pause/resume · R reset · rods stay rigid, bob 2 leaves the fading trail.