$18\mathrm{.}60$ A $5\mathrm{.}00g$ charged insulating ball hangs on a $30\mathrm{.}0cm$ long string in a uniform horizontal electric

field as shown in Figure $18\mathrm{.}52.$ Given the charge on the ball is $0\mathrm{.}89C,$ find the strength of the

field.

Figure $18\mathrm{.}52$ A horizontal electric field

causes the charged ball to hang at an

angle of $8\mathrm{.}00.$