A small object has a mass of $6\mathrm{.}0{10}^{-3}kg$ and a charge of $-21C.$ It is placed at a certain spot where there is an electric field. Wher released, the object experiences an acceleration of $2\mathrm{.}6{10}^3\frac{m}{s^2}$ in the direction of the $+x$ axis. Determine the electric field, inclu sign, relative to the $+x$ axis.