Source: https://guthlabs.ai/docs/instruments/friction-force-calculator/mechanism/

instrument mechanism / verified-clean

# Friction Force Calculator mechanism

The inspectable method record for Friction Force Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The coefficient formulas are standard under the Coulomb-friction model, but the specification is incomplete for its claimed motion and friction outputs. Add applied/net tangential force, define actual static friction versus maximum static friction, and specify the mass-plus-angle configuration and angle units before release.

- f_s,max=μsN is the standard maximum static-friction magnitude, not necessarily the actual static-friction force. When the object is stationary, actual static friction is min(|F_t|, μsN), where F_t is the net tangential driving force.

- f_k=μkN is the standard kinetic-friction magnitude only while the surfaces are sliding; it must not be reported as the friction force for a stationary object.

- The supplied inputs do not include an applied or net tangential force, so motion yes/no and actual static friction cannot be determined.

- If normal force is derived from mass and angle, the needed formula and physical configuration are unspecified. For a simple incline with no other forces, N=mg cos(θ), but other configurations produce different normal forces.

## Units and conventions

- μs and μk are dimensionless and nonnegative.

- N is a normal force measured in newtons; if mass is supplied, mass is in kilograms and g is in m/s².

- Angles are assumed to be in degrees in these test vectors; the implementation must explicitly define degrees versus radians.

- The motion tests assume F_t is the net tangential driving-force magnitude in newtons, with no other tangential-force ambiguity.

- Friction outputs are magnitudes; the friction direction is opposite the impending or actual motion.

- The illustrative μ table must not be treated as a material-certified measurement.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "mu_s": 0.5,
    "mu_k": 0.3,
    "normal_force_N": 100,
    "tangential_force_N": 20
  },
  "expected_outputs": {
    "maximum_static_friction_N": 50,
    "kinetic_friction_if_sliding_N": 30,
    "actual_friction_N": 20,
    "motion": "no"
  },
  "working": "Maximum static friction = μsN = 0.5 × 100 = 50 N. Since |F_t| = 20 N ≤ 50 N, the object remains stationary. Actual static friction = 20 N. If it were sliding, kinetic friction would be μkN = 0.3 × 100 = 30 N."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The extreme-magnitude vector causes μN = 10^616 to overflow to Infinity in ordinary JavaScript arithmetic. The calculator should reject or flag the nonfinite result instead of presenting it as a valid physical friction force.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/friction-force-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/friction-force-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/friction-force-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`