A linear motor gives a rocket a running start. The physics is unforgiving in one direction: track length grows with the square of exit speed, and it's capped by how many g the payload survives. Dial the exit speed and the g-limit and watch the track stretch to tens of kilometers — and the switching electronics into the kilohertz.
To reach speed V at acceleration a you need L = V²/2a. Double the exit speed and the track quadruples. That's why kinetic assist stays modest: a few hundred m/s is cheap, multi-km/s means tens of kilometers of guideway.
People tolerate ~3 g, hardened cargo ~10–20 g. Lower g means gentler acceleration means a longer track for the same exit speed. Passengers and high exit speed are nearly incompatible — this is a cargo game.
The traveling magnetic wave must commute coils in step with the vehicle as it accelerates — switching frequency climbs into the kilohertz at exit — while holding a millimeter levitation gap. Fast power electronics and control, not a person.