1. The problem statement, all variables and given/known data In my book , the author stated that working stress is the maximum stress premitted under design load . Whereas the allowable stress is given by below ( refer to the notes attached ) http://imgur.com/a/YnimQ 2. Relevant equations 3. The attempt at a solution So , the working stress is the maximum stress before the object will fail ? Allowable stress is the stress that we determine ourselves ? If the working stress is 4000N , by safety factor of 2 , so the allowable stress is 2000N ? here , the maximum stress that we can apply is 2000N due to safety reason ? Correct me if i am wrong .