Terminal Velocity Calculator mechanism

Model scope

The mathematical formula is correct for steady quadratic drag with constant Cd. Before release, explicitly document or expose g, specify required units and validation constraints, and replace the laminar wording with an accurate statement such as 'assumes constant quadratic-drag coefficient, typically appropriate over a specified Reynolds-number regime.'

• The formula v_t = sqrt(2mg/(rho Cd A)) is the standard terminal-speed formula for quadratic drag, assuming constant gravitational acceleration, constant drag coefficient, and SI-compatible quantities.
• The specification omits g from the listed inputs and does not explicitly state whether g is fixed at 9.81 m/s^2 or configurable; this is an exact implementation ambiguity.
• The honest label 'laminar-simplified drag' is misleading: quadratic drag is generally used at sufficiently high Reynolds number, while many laminar regimes are better modeled with linear Stokes drag.
• The spec does not define valid input constraints such as mass > 0, Cd > 0, cross-section area > 0, and air density > 0.

Units and conventions

• mass is in kilograms
• cross-section area is in square metres
• air density is in kilograms per cubic metre
• Cd is dimensionless
• g is assumed to be the fixed standard value 9.81 m/s^2 unless explicitly made an input
• terminal velocity output is in metres per second

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "mass": 0.1,
    "mass_unit": "kg",
    "Cd": 0.47,
    "area": 0.01,
    "area_unit": "m^2",
    "air_density": 1.225,
    "air_density_unit": "kg/m^3"
  },
  "expected_outputs": {
    "terminal_velocity": 18.46,
    "terminal_velocity_unit": "m/s"
  },
  "working": "Use g = 9.81 m/s^2. Numerator = 2 × 0.1 × 9.81 = 1.962. Denominator = 1.225 × 0.47 × 0.01 = 0.0057575. Ratio = 1.962 / 0.0057575 = 340.7729. Square root = sqrt(340.7729) = 18.4600 m/s, so terminal velocity ≈ 18.46 m/s."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The specification provides no stated validation behavior for zero or negative density, drag coefficient, or area, so the raw formula can produce division by zero or a non-real square root. It also returns only a speed magnitude, leaving the sign convention ambiguous. The formula has no true multi-regime branch, so a correct implementation must explicitly reject invalid-sign inputs rather than silently treating them as a second physical branch.

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-tranche2/tranche2-results.json
• BOUNDARY_HAZARD_CATALOG.json