The correct scientences is " I am mechanic" . I can not say" I am mechanism "

mechanism mean the way or process by which you do something ......for example the mechanism of photosynthesis involve two steps while Mechanics (Greek Μηχανική) is the branch of science(physics) concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment.....................for example he is a mechanic, not mechanism and in the first example we cannot use mechanics instead of mechanism