Four uniform spheres, having masses mA = 400 kg, mB = 700 kg, mC = 2000 kg and mD = 400 kg, encompass (x, y) coordinates of (0, 50 cm), (0, 0), (-80 cm, 0), and (40 cm, 0), correspondingly. Determine the total gravitational force F2 on sphere B due to the other spheres?