English: Versions of Newton's laws in (1+1)D spacetime using minimally frame-variant traveler-point variables^[1] (proper time τ, proper velocity w, and proper acceleration α) designed to work at any speed in flat spacetime, and also locally in curved spacetimes and accelerated frames provided that geometric forces (like gravity and centrifugal) are approximated as proper frame-variant forces f, even though they do not have corresponding felt forces ξ detectable e.g. by a traveler's cell-phone accelerometer.

Notation: The "three-line equals" (≡) flag definitions, the hooked arrows track logical implications, and the "double-arrow equals" (⇔) connect kinematic relationships to physically conserved quantities like momentum p, total energy E, and kinetic energy K. Equalities without the superposed circle (i.e. = or ≡ instead of ^o) also work for the corresponding 3-vector^[2] and scalar quantities in (3+1)D.