Originally Posted by

**jonny2x4** Hello all, wonder if you can help me? I'm an engineering student but obviously haven't been studying that hard because I can't work out this problem:

I want to create a spiral, I know the total length if it were stretched out and I know the thickness...the best way I can describe it is as if you had a bit of rope that was 5mm thick and 4m long, then you coiled it up in a spiral on a table or something. The question is, is there a general formula to work out how many revolutions the coil would have and what the overall diameter would be?

Any help much appreciated!