Four identical charged spheres are placed in fixed positions on a horizontal, frictionless lab table in the square configuration shown below. The sides of the square are 25. 0 cm long. The charge on each sphere is -8. 30 X 10 - C and the mass of each sphere is 4. 70 kg. Sphere D is then released from its position and allowed to move. Calculate the acceleration of sphere D at the moment that it is released. Assume that gravitational forces are negligible. (4) D C