Uh.. actually, you missed an important part.
One does not become a mechanical engineer just by choosing it as a branch in any college. After getting the said branch,, there are 4 years, 8 semesters full of gruelling practicals, projects, assignments, tutorials, vivas, mid sem exams and end sem exams. All these need to be cleared in the course of 4 years after which one gets the B Tech degree.
This part is very important for all those people who say that life after 12th is chill. It never was, never is and never will be.