Marble Run: Friction & Gravity Test (2D)

Track & Fleet

Marble count 6

Hill intensity 1.00

Dynamics

Gravity multiplier 1.00x

Rolling friction μ 0.15

Readout

Marbles active

Avg speed

0.0 u/s

Elapsed

0.0 s

Laps total

Stalled now

Track length

0 u

Under the hood

Each marble is a point bead constrained to a closed track. Its speed along the path v updates every fixed step from the true tangential forces:

dv/dt = g·sin(φ) − μ·g·cos(φ)·sign(v)

where φ is the local slope angle of the track (from the tangent at the marble's arc-length position) and μ is the rolling-friction coefficient. On a downhill stretch gravity's tangential component g·sin(φ) accelerates the marble; friction always opposes motion. Raise μ enough on a steep uphill segment and a marble's speed decays to zero before it crests — it stalls in place until the track (or your friction setting) lets it move again, exactly the "friction wins" case the title tests.

Fixed-step integration (240 Hz) keeps the stall condition numerically stable.
The track is a closed hill-modulated loop; arc length is resampled whenever hill intensity changes.
Gravity multiplier scales g directly — above 1× marbles crest hills that would otherwise stall them at 1×.

Track (bead-on-wire) Marble (color = individual) Stalled (friction > gravity here)