Finally, consider the gravitational force generated by a spherically symmetrical massive object. the magnitude and direction of such a force are given by newton's law of gravity: f⃗ g=−gm1m2r2r^, where ds⃗ =drr^; g, m1, and m2 are constants; and r> 0. find u(rf)−u(r0)=−∫rfr0f⃗ g⋅ds⃗ . express your answer in terms of g, m1, m2, r0, and rf. view available hint(s)