56. Gravitational force due to a mass The gravitational force on a point mass m due to a point mass M is a gradient field with potential U(r) = GMm/r, where G is the gravitational constant and r = Vx* + y> + 77 is the distance between the masses. a. Find the components of the gravitational force in the x-, y-, and z-directions, where F(x, y, z) = VU(x, y, z). b. Show that the gravitational force points in the radial direction (outward from point mass M) and the radial component is F(r) = GMm/r*