Ludwik,
I beg to disagree, unit vectors define a direction. You can't combine ups
with to the rights any more then you can meters and meters/second. Your
correct that they are always associated with other units but so are all the
other units of physics beyond the fundamental ones. They seem to have more
in common with prefixes like say nano, that always need other units to say
a billionth of what.
Gary
Gary Karshner
St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU