(Simple Mechanics of Materials) Is there a sign convention for where x=0 is and x=L is on a simple horizontal axially-loaded rod? It seems that no matter where the fixed end is, the x=0 end is always on the left end of the rod, so is that a defined convention or can we choose either end to be where x=0?

  • $\begingroup$ Assuming the rod is statically determinate and has one free end and one fixed end $\endgroup$
    – Mark
    Commented Apr 9, 2017 at 1:47
  • $\begingroup$ Please edit your question instead of adding informative comments to your own question. $\endgroup$
    – Wasabi
    Commented Apr 9, 2017 at 1:49

1 Answer 1


You can choose whatever you want. Or, more importantly, whatever is best to help solve your question.

There is a natural bias to put $x=0$ on the left side simply because, well, we're used to having the positive number line (from 0 to $L$) go to the right. But you could obviously just mirror the structure in any case to better suit your needs, or simply go with the positive number line to the left.

Whatever works.


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