Atwood Machine Solver implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-272

Effect

Computation or source lookup only

Input and validation requirements

A nonzero pulley inertia combined with zero pulley radius makes I/r^2 undefined. Without explicit input validation, the solver can propagate undefined or nonfinite values into acceleration and tension instead of rejecting the input.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "m1_kg": 2,
    "m2_kg": 5,
    "pulley_I_kg_m2": 0,
    "pulley_radius_m": 0.2,
    "g_m_s2": 9.81
  },
  "expected_outputs": {
    "acceleration_m_s2": 4.2042857143,
    "tension_m1_N": 28.0285714286,
    "tension_m2_N": 28.0285714286
  },
  "working": "I/r²=0/0.2²=0. Denominator=2+5+0=7 kg. Numerator=(5-2)×9.81=29.43. a=29.43/7=4.2042857143 m/s². T1=2×(9.81+4.2042857143)=2×14.0142857143=28.0285714286 N. T2=5×(9.81-4.2042857143)=5×5.6057142857=28.0285714286 N; with an ideal massless pulley, both tensions are equal."
}

Other records

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