Thanks for explanation , I now got it. Will read more about inertia and resistance and come back with a bunch of questions.
Now , I know these are very basic questions. I am a student of 9th standard and in our country these things are in the syllabus of 11th standard. Actually , proper Physics starts in 11th standard only.I was just having some interest in the subject and finishing parts of the syllabus of higher classes which I think I can grasp without a teacher. I feel the books , the internet and this forum is enough for a clear idea beforehand.