I wanted to know if there exists a constant with a unit meter-time or say length-time. Dimensionally [LT]. I have searched browsed a lot. Is there any quantity arising with such a unit?

  • 2
    $\begingroup$ The product of Planck length and Planck time? $\endgroup$ – Qmechanic Jan 24 at 19:24
  • $\begingroup$ I got that quantity with unit m-s by dividing a Constant with units same as planks constant and a Force. $\endgroup$ – suraj deshmukh Jan 24 at 19:31
  • $\begingroup$ @Qmechanic: For the record, that works out to be $G h /c^4 \approx 5.5 \times 10^{-78} \text{ m}\cdot\text{s}.$ $\endgroup$ – Michael Seifert Jan 24 at 19:54

One can probably always derive some contrived example.

If I characterize flow in a pipe by the property of "residence" $R$, for example, where the time required for some slug of liquid to pass through a pipe of length $L$ and cross-sectional area $A$ is $t=RL/A$, then this property would have units of meter-second.

If I wished to characterize the predominance of some linear commodity over time, then I might evaluate the length multiplied by the time it's been used: "No. 12 AWG copper wire has predominated in U.S. house construction since electrification, with a total extent of use of 2.4 trillion meter-years."


Not a fundamental one. See list here.


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