Aforce of 5.25 newtons acts on an object of unknown mass at a distance of 6.9 × 108 meters from the center of earth. to increase the force to 2.5 times its original value, how far should the object be from the center of earth?

The force between two objects is calculated through the equation, 
                        F = Gm₁m₂/d²
where m₁ and m₂ are the masses of the objects. In this case, an unknown mass and Earth. d is the distance between them and G is universal gravitation constant. 

In the second case, if the force is to become 2.5 times the original and all the variables are constant except d then,
                       2.5F = Gm₁m₂ / (D²)
                                D = 0.623d

Subsituting the known value of d,
                                D = 0.623(6.9 x 10^8) = 4.298 x 10^8 m
                           

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