Question

we cant push a car sitting inside it and move it why

Answer 1

we can't push a car sitting inside it and move it because it contains more force than me or it is more heavier to push from inside sitting the car .

Answer 2

Well.....!!!
According to Newton's first law of motion, "Every body continues to be in the state of rest or in uniform motion, until an external force acts upon it"
so in this equation you can see that Newton has used the word EXTERNAL.........
and what's the difference between external and internal forces is.........that the external is unbalanced......and the internal force is balanced.........
and you know that the car will only move......when there's an unbalanced force applied which is possible only from outside the car....,.......
and that's why you can't move it from inside..........