Source: https://guthlabs.ai/docs/instruments/friction-force-calculator/
instrument / verified-clean
# Friction Force Calculator
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## Ledger state
The current ledger marks this instrument verified clean within the source-bound verification corpus.
**Area**: Physics — Kinematics/Projectiles/Orbits, Forces/Energy/Momentum, Rotational Dynamics, Gravitation, Oscillations/Waves, Optics, E&M Fields, Relativity, Quantum, Statistical Thermo
**Tranche**: tranche-4
**Evidence ID**: t4-250
**Ledger rows**: 1
No ledger note is attached.
## Review findings
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.
### Formula and scope findings
- 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.
### Unit assumptions
- 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.
## Boundary hardening
**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.
## Errata and corrections
No applied erratum is attached to this unique-name record.
## Inspectable example
4 review vectors are recorded. One source-bound sample is shown below.
````
{
"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."
}
````
## Related workflows
No source-defined multi-instrument workflow membership is recorded.
## Sources and evidence
These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.
- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`
- `evidence-tranche4/tranche4-results.json`
- `BOUNDARY_HAZARD_CATALOG.json`