1. The problem statement, all variables and given/known data In calculating stresses, how do we determine when we have a negative in front of the question and when we do not have it. I am really confused, meaning I have not understood the concept, but the examples I am looking at some have got σ= My/I whilst others have σ= -My/I. 2. Relevant equations σ= My/I σ= -My/I Hopefully they get uploaded properly. The first two use the first equation, whilst the the other two use the second equation Thanks for the help.