x1 measures to be x2 [li; number] kilogram-meters-per-second by standard x3
This is a a named unit derived from the SI base units, just like the Joule and the Ohm; the difference is that there is no special name for it in standard SI. This word is synonymous with "pi'ai ki'ogra mitre fei'u snidu". x1 can be a strictly-spatial linear momentum (or a coordinate or magnitude thereof), etc.: any dimensionful quantity with dimension of mass times distance per second. See also: sirmpetu, klaicnampe.