I don't know if this is a foolish question or a decent one, I don't know if there is any official subjective answer to this, this query is popping in my mind and lately I can't stop myself from thinking what the scientific or 'physical' cause might be....
Please don't mind if it is a question of a darn fool cause I am only a high schooler from India. XD
Suppose a strong man of mass M is pushing a wagon with a force F ,which contains load of same mass M. His force overcomes the static friction and acceleration is caused in the system of the load and a wagon and it moves.
But consider a case, where the man of mass M is standing in the wagon(in place of load of mass M) and he applies the same force F. The wagon does not move. Whatever mass of the man is and how brute the force he applies, there is no acceleration in the system. Thinking as a Layman, this is simple. But what is the theoritical physics behind this?
First I thought that the weight of the man acting downward is restricting any acceleration, but it is not the case because the man can push the wagon which is containing a loaf of his same mass exerting the same weight , if he has the strength.
If anyone guides about the correct physics behind this, I will be grateful to that person. Because of this query , I sometimes lose my atten on other subjects.
My drawing is not very good but attached is a rough diagram of the two scenarios
Best wishes
A science aspirant and lover from India