Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

What physical quantity has SI unit $\mathrm{kg}/\mathrm{m}$?

For example, the physical quantity with SI unit $\mathrm{kg}\cdot\mathrm{m}/\mathrm{s}^2$ is force $F$ and the physical quantity with SI unit $\mathrm{m}/\mathrm{s}^2$ is acceleration $a$.

share|cite|improve this question
I didn't downvote you, but I can guess why someone did. Many different quantities can have the same units. For example pressure, tensile strength and energy density have the same units. Another example is angular momentum and action. Your example could correspond to a linear density (the mass of something, such as a rope, per unit length). But it could be any number of physically different things that happen to have the same units. – Michael Brown Jan 11 '13 at 12:02
Symbols themselves are meaningless. They're just notation. A quantity with SI units $\mathrm{kg}\cdot\mathrm{m}/\mathrm{s}^2$ we could call a force and the usual convention is to use the letter $F$ to denote a force. Perhaps your question should be edited to ask about the meaning of a quantity with SI units $\mathrm{kg}/\mathrm{m}$. That could be a linear mass density. – Wouter Jan 11 '13 at 12:04
Gravitational Potential per Gravitational Constant – centralcharge Jun 30 '13 at 7:32

One is the linear mass density ($\mu$) of fibers. There are the units $1 \:\mathrm{tex} = 10^{-6} \:\mathrm{kg/m}$, $1 \:\mathrm{dtex} = 10^{-7} \:\mathrm{kg/m}$ and $1 \:\mathrm{den} = {1\over 9} \cdot 10^{-6} \:\mathrm{kg/m}$. See and

share|cite|improve this answer

As far as I know $\mathrm{kg}/\mathrm{m}$ is not a commonly used unit in physics. It might, however, be used for instance when comparing the linear density of objects that might be thought of as one-dimensional, like ropes or railway tracks. The symbol used to denote it would probably vary from case to case, but $\rho$, as used for volume densities, might be suitable if you don't have a better idea.

share|cite|improve this answer
A commonly used symbol to denote linear mass densities is $\mu$, but in the end the symbol is not that important. It's merely a tool to allow different people to correctly interpret each other's expressions. – Wouter Jan 11 '13 at 12:07

The physical quantity for $\mathrm{kg}/\mathrm{m}$ is the linear density or linear mass density or linear mass which defines mass per unit length.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.