Source: https://guthlabs.ai/docs/instruments/2d-collision-solver-oblique/implementation/

instrument implementation / implementation-contract

# 2D Collision Solver (oblique) implementation

A source-bound implementation contract for 2D Collision Solver (oblique); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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

[01**Overview**](<https://guthlabs.ai/docs/instruments/2d-collision-solver-oblique/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/2d-collision-solver-oblique/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/2d-collision-solver-oblique/qualification/>)

## 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`