nx_acceleration.nx

nx_acceleration.nx -- 3D acceleration vector + Newton's second-law composition with nx_force. Layer 1 physics per [[feedback-engineering-sciences-bits-up-3d-print-first]]. Unit: Q14 metres-per-second² (m/s²). 1 Q14 unit = 1/16384 m/s² = 61 µm/s². Range fits i64 to ±5e14 m/s² -- vastly exceeds any engineering use (rocket sled peaks ~50g ≈ 490 m/s², centrifuge ~10⁶ m/s²). Newton's second law composition (F = ma): nx_force_from_mass_accel(mass_kg_q14, accel) -> *NxForce This is the second cross-primitive composition demo in the physics layer (after nx_torque_from_position_force). Verified by smoke roundtrip: gravity acceleration × 1 kg produces the same NxForce as nx_force_gravity_on_kg(1 kg) within Q14 rounding. Composes: nx_force (for F = ma return type) nx_isqrt (magnitude via Q28 sum-of-squares) nx_i128 / nx_muldiv_i64 (overflow protection) Per [[feedback-four-pillar-design-aware-response]] (META-CARDINAL): all multi-line subtractions use named temporaries (Pillar 2 recommendation for the nishilang-multi-line-binop gotcha). All value transforms use let-immutable + pure helpers (no inline `if x < 0 { x = 0 - x }` -- composes nx_abs if needed). license_tier: ORIGINAL