Answer:
a) 75 N
Explanation:
Newton's law of universal gravitation states that the force between two objects is:
F = mMG / r²,
where m and M are the masses of the objects, G is the universal constant of gravitation, and r is the distance between the objects' centers of mass.
When the object is 500 km above the surface:
100 N = mMG / (1,000,000 m + 500,000 m)
mMG = 1.5×10^8 Nm
When the object is 1000 km above the surface:
F = (1.5×10^8 Nm) / (1,000,000 m + 1,000,000 m)
F = 75 N
Answer is A.