Gravity Sand Pendulum

Pendulum Sand Circle

Paint hypnotic “sand table” patterns with a simulated 2-D pendulum. Physics includes damping, gravity, slight axis anisotropy (ε), and Earth’s rotation (Coriolis Ω·sinφ). Drawings accumulate on a sand-colored layer while the plumb-bob sweeps above. Tweak the release position, gravity, damping, ellipticity, latitude, time scale, and line style—or hit presets to bloom flowers, lissajous knots, or a Foucault precession.

How to play

• Set the release (radius/angle) and tap Set Start & Release.
• Adjust Length, Gravity, Damping, Ellipticity to sculpt the curve.
• Turn Coriolis up to watch the plane precess (Foucault-style).
• Use Line Width / Opacity / High-Contrast to taste.
• Clear Trail wipes the sand; Save PNG exports your art.

Recommended start (to match your screenshots)

These produce the neat rosette you showed:

• Preset: Flower (slight ε) (or use the values below)
• Release: Radius 35 cm, Angle 30°, Push 0 cm/s, Direction 0°
• Pendulum: L = 1.00 m, g = 9.81, γ = 0.015 s⁻¹, ε = 3%
• Earth/Frame: Latitude 0°, Coriolis 0×Ω, Canvas Spin 0°/s, Time Scale 1.0×
• Sand/Trail: Line Width 2.2 px, Opacity 100%, High-Contrast ON, Auto-Fade OFF