What is the magnitude of the force on the $8\mathrm{.}0\mathrm{????}\mathrm{????}$ charge in the middle of the figure due to the four other charge Express your answer with the appropriate units.

(Figure 1) shows five electric charges. Four charges with the magnitude of the charge 2.0 nC form a square with the size a = 3.0 cm. Positive charge with the magnitude of q = 8.0 nC is placed in the center of the square.