The gravitational force f on a rocket at a distance r from

Question

Question: The gravitational force, F, on a rocket at a distance, r, from the center of the earth is given by

F = k/r²

Where k = 10¹³ newton · km². When the rocket is 104 km from the center of the earth, it is moving away at 0.2 km/sec. How fast is the gravitational force changing at that moment? Give units. (A newton is a unit of force.)