2D Collision Solver (oblique) 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

t4-227

Effect

Computation or source lookup only

Input and validation requirements

A zero-total-mass input makes the solver's mass denominator vanish, producing undefined post-collision velocities unless the instrument validates and rejects the input. The branch test also exposes a required approaching-versus-separating decision that a solver must implement consistently.

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": 1,
    "m2": 1,
    "v1": [
      2,
      1
    ],
    "v2": [
      -1,
      0
    ],
    "impact_angle_deg": 0,
    "line_of_centers_unit": [
      1,
      0
    ],
    "e": 1,
    "velocity_unit": "m/s"
  },
  "expected_outputs": {
    "v1_prime": [
      -1,
      1
    ],
    "v2_prime": [
      2,
      0
    ],
    "velocity_unit": "m/s"
  },
  "working": "n=(1,0), t=(0,1). Normal components: v1n=2, v2n=-1; tangential components: v1t=1, v2t=0. For equal masses and e=1: v1n'=((1-1)*2+(1+1)*1*(-1))/2=-2/2=-1. v2n'=((1+1)*1*2+(1-1)*(-1))/2=4/2=2. Tangential components are unchanged, so v1'=(-1)n+1t=(-1,1) and v2'=2n+0t=(2,0)."
}

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