>i have mathematica version 4.0, student type...
>in physics class we use version 3.0 and a package called mechanics, which includes functions such as ListPlot, Poly, and Coordinator.
>where can i get this package for mathematica version 4.0 and what is it called? (structural mechanics or mechanical systems?)
>thanks for your help
The best source will be your physics instructor, department, or perhaps your notes from early in the class. As another reply mentioned, it is possible that the package was something developed specifically for the course or was a supplement to your textbook. In either case, we at Wolfram will be unlikely to know much about it or have a copy.
As another reply mentioned, V3.0 packages usually will work with V4.0, so if you have a copy of the package, just try it.
Finally, Wolfram does sell an application pack called Mechanical Systems which is the only package that I know of that comes close to what you are describing. See store.wolfram.com.