Question 1090222
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When (and if) the body is placed inside the Earth at the radius "r" (the depth R-r), then the only the part of the Earth 
which is inside of the sphere of the radius "r" creates (produces)  the gravity.


The exterior spherical layers  r < s < R  produce ZERO gravity integral force.

In other words, they do not make gravity force.


This fact is known from the Newton times to all who know/knows Physics.


And this effect MUST be accounted for in the solution of problems like this one.


The situation (and the solution) is different comparing with the case when the body is lifted ABOVE the Earth surface.



Therefore, the solution by @Fombitz is incorrect and must be redone.



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To get the feeling of this effect, imagine that the body is placed exactly at the center of the (spherical) Earth.


What is the gravity force and what is its direction in this case ?


The answer (quite unexpected ?)  is: the gravitation force is ZERO in this case.


          Did I say "unexpected" ?  - But if you think 5-10 seconds on it, you will get that is is correct 
                                      and nothing else can happen (due to symmetry).
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