An object at a distance of 6400km from the centre the earth weights 50 Newton
what will be its weight if
it is shifted to 12800 km from the center of the earth?

12.5N

Explanation:

From newton law of universal gravitation F= GmM/d2.

that means Force is inversely proportional to the square of the distance apart.

F1= 50N, d1=6400km

F2=?, d2=12800km

F1/F2=d2×d2/d1×d1 so we have 50/F2= 12800×12800/6400×6400...F2=6400×6400×50/(12800×12800)=12.5N

that would be because of both gravity and friction. so     c