Question 5 Three identical point masses, each of mass 1kg lie in the x-y plane at points (0, 0), (0, 0.2m) and (0.2m, 0). The net gravitational force on the mass at the origin is (a) 1.67x10 +jN (b) 3.34 x 10-0+N (c) 1.6710%-N (d) 3.3410-10+jN C 0/1pts -9 correct Question 6 You put your spacecraft into a circular orbit around planet Z, which has half the radius of earth and has one-quarter earth's mass. Compared to being in an orbit of the same size around earth, how are the kinetic energy K and gravitational potential energy U for your spacecraft different when in orbit around planet Z? K is less and is greater (less negativel Kis greater and is greater (less negativel none of these.. K is less and U is less (more negativel Kis greater and U is less more negative) 0/1 pts correct Question 9 In some region, the gravitational field is zero. The gravitational potential in this region Must be a variable Must be zero Must be constat 0/1 pts Cannot be zero