In science, some quantities have units. e.g. Mass (kg) , time (s), distance (m).

But what about quantities such as velocity (m/s) and acceleration (m/s/s) whose units are a combination of fundamental units and not a single unique unit.

What is the correct English term for something like m/s ? Is it a unit or not, or is there another word to describe such combination of units?

I'm looking for a one-word answer. The ... of velocity is m/s.

  • Welcome. You could have answered this easily by Googling 'unit of velocity' . Then you would have found something like this, The SI unit of distance and displacement is the meter. The SI unit of time is the second. The SI unit of speed and velocity is the ratio of two — the meter per second. physics.info/velocity Nov 5 '15 at 12:19
  • Velocity is expressed in units of distance divided by time.
    – Hot Licks
    Nov 5 '15 at 12:19
  • It's not really a subject for this site, but you should look up "fundamental units of measurement". Velocity can be expressed as a combination of fundamental units, therefore doesn't 'deserve' such a unit of its own.
    – JHCL
    Nov 5 '15 at 12:20
  • I've voted to close. This question could have been answered with easily available online resources. Nov 5 '15 at 12:21
  • @JHCL - Velocity can be expressed as a fraction of C, a fundamental constant.
    – Hot Licks
    Nov 5 '15 at 12:23

The technical term for this is a derived unit, but in everyday speak/text I think using the word unit is totally acceptable.

See for example the Wikipedia page ab out SI Derived Units.

  • 1
    Of course, what's "derived" is more a matter of culture than fact. Velocity can be expressed as a fraction of C, the speed of light, which is a fundamental constant and which is used in most modern schemes to accurately determine time and distance.
    – Hot Licks
    Nov 5 '15 at 12:22
  • Although I've voted to close, I think this answer does provide useful background information. I'll just add that many named units (e,g, the herz) are actually derived units. One hertz is one cycle per second. The truth is that any unit at all can be derived from a combination of other units. (as hinted at by HotLicks' comment) Nov 5 '15 at 12:26
  • The whole bit about "I think" and "everyday speak" is completely uncalled for weasel wording. If the technical term is derived unit, then that is a unit by definition. The name says just that. What do you mean "I think", "perhaps", "in everyday text"? You yourself only just said that unit was in fact the perfectly proper technical term and now you're backing down? Why?
    – RegDwigнt
    Nov 5 '15 at 13:14
  • @RegDwigнt I don't see which part of my answer was unclear... I noted the term (derived unit) which is the correct one, and noted that another term (unit) - which is a superset of the first - can also be used. What are you upset about?
    – fgysin
    Jun 16 at 6:57

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