I am not trained in physics but find it extremely interesting to read about. As I was reading a book on Einstein it talked about about gravitational force being equal to inertial mass. A good deal of the discussion talked about a man in a box and the inability to distinguish one effect from the other and what would happen to a beam of light through a pin hole.(adsbygoogle = window.adsbygoogle || []).push({});

The answer to my question is probably painfully obvious but I did some searches and could find nothing to answer it.

I thought about this same guy in a box that is at the interface of two gravitational fields where there is a line where the pull is equal and the pull of either field is greater on their side of this line.

If this box intersected this line I would guess that the amount of force to accelerate the box would decrease sharply. If the box had equal mass on either side of the line including the man what would the effects be. He would feel a pull from both directions so what conclusion would he draw. As explained in the book if a pin hole let light in it would curve in the direction of gravity. If there where three holes on on the line and one on either side he would see a straight line and two curving rays going opposite ways. Again what conclusion would he arrive at.

I am sure all this is very obvious but when I think about two identical boxes each located across this line but one equally distributed and one with more mass on one side or the other, it seems to me that the amount of force to accelerate it or the weight of the box could be vastly different. I know they say that the guy in the box could not tell if he was feeling gravity or acceleration but what would he think if he felt gravity on both sides.

My simple mind cannot comprehend what any of this would mean. What if the guy sat on the floor on one side of the line and saw a light that was on the other side of the line as it curved away from the pull he felt. How would he calculate or determine what was going on?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Gravitational force = inertial mass

**Physics Forums | Science Articles, Homework Help, Discussion**