Makes enough sense to me but curious why specifically? Are they quieter or less dangerous below that size / weight?

> Are they quieter or less dangerous below that size / weight?

F = m*v^2

Not F (force, which is m*a), but Ki (kinetic energy):

Ki = mv²/2

The FAA Part 107 examination claims this is because lightweight drones pose less harm to life (when accompanied by rotor guards.)

There isn’t much of an actual reason, the FAA has been all over the place without much logic when it comes to drone regulations.