5. (3 pts) A 4 kg mass is located at x=0. A 6 kg mass is located at x=4 meters. Where should you put a third massr m=1 kg such that the net force on the 6 kg mass is 38 N in the negative x direction? 6. Three spheres are lined up as shown below, the distance between each sphere is L. A] (4 [315) Find the gravitational potential energy of the system of masses. Your answer should be in terms otG, M and L. B} (4 pts) How much work is needed to move the three masses into the shape of an equilateral triangle with sides of length L? Your answer should be in terms of G, M and L