Doppler Effect Calculator (sound)

Inspectable records

Ledger state

The current ledger marks this instrument verified with errata that must be applied at binding time.

Area

Physics — Kinematics/Projectiles/Orbits, Forces/Energy/Momentum, Rotational Dynamics, Gravitation, Oscillations/Waves, Optics, E&M Fields, Relativity, Quantum, Statistical Thermo

Tranche

tranche-5

Evidence ID

t5-075

Ledger rows

1

No ledger note is attached.

Review findings

The core classical still-air Doppler formula is standard, but the specification needs explicit sign mappings, a defined shift-percent formula, unit validation, and domain constraints. The honest label is appropriate only when motion is relative to a stationary medium and relativistic, wind, and multidimensional effects are excluded.

Formula and scope findings

• The ±/∓ signs are not explicitly mapped to approaching versus receding motion; a standard convention is approaching: f_obs=f_src(v+v_obs)/(v-v_src), receding: f_obs=f_src(v-v_obs)/(v+v_src), with velocities measured along the source-observer line relative to the still medium.
• The output shift percentage is specified but its formula is missing; it should be shift_percent=100*(f_obs-f_src)/f_src, assuming f_src is nonzero.
• The formula assumes collinear source and observer velocities and a stationary, homogeneous medium; these constraints are not stated in the input specification.

Unit assumptions

• All velocities must use the same unit before substitution; the examples use m/s unless explicitly converted.
• The speed of sound is 343 m/s for still air at 20 °C.
• Source and observer velocities are measured relative to the medium and along the line joining source and observer.
• Shift percentage is signed relative to the emitted frequency: positive means an increase and negative means a decrease.
• The source frequency must be greater than zero.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The calculator breaks or must reject an exactly sonic approaching source because the Doppler denominator becomes zero. It is also vulnerable to materially incorrect results if the approaching/receding branch or velocity sign convention is inferred ambiguously.

Errata and corrections

Tranche errata

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "source_frequency_hz": 440,
    "speed_of_sound_m_s": 343,
    "source_velocity_m_s": 0,
    "observer_velocity_m_s": 0,
    "motion": "stationary"
  },
  "expected_outputs": {
    "observed_frequency_hz": 440,
    "shift_percent": 0
  },
  "working": "Stationary case: f_obs=440*(343+0)/(343-0)=440*343/343=440 Hz. shift%=100*(440-440)/440=0%."
}

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_WITH_ERRATA
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json