$($II $mmh$ The drawing shows three point charges fixed in place. The charge at the coordinate origin has a value of $q_1=+8\mathrm{.}00C$; the other two charges have identical magnitudes, but opposite signs: $q_2=-5\mathrm{.}00C$ and $q_3=+5\mathrm{.}00C.($a$)$ Determine the net force $($magnitude and direction$)$ exerted on $q_1$ by the other two charges. $($b$)$ If $q_1$ had a mass of $1\mathrm{.}50g$ and it were free to move, what would be its acceleration?