Question 1173967
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            For your info,  and for the info of the person who created/composed this problem.



For an object located deeply inside the Earth globe,  this statement is  INVALID,

that the weight of such an object is inversely proportional to the square of the distance from the  Earth center.


In this case,  outer layers of the  Earthen globe produce  ZERO  net gravitational force,

and only interior mass of the  Earthen globe participates to make the net gravity force.



As a result,  the inverse proportionality law  DOES  NOT  work for the bodies inside the  Earthen globe.



For example and as a consequence of this fact,  the weight of the body located  AT  THE  CENTER 
of the  Earthen globe is equal to  ZERO,  but not an infinity . . . 



It was discovered by sir  Isaak  Newton more than  330 years ago,  and is well known fact since then for all who knows the subject.



THEREFORE,  the part  (b)  of your problem can only confuse a professional reader,

and makes it clear that the person who created this problem is unfamiliar with elementary Physics,

so you better take it off . . . 



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