A stone tied to \( 180 \, \text{cm} \) long string at its end is making \( 28 \) revolutions in horizontal circle in every minute. The magnitude of acceleration of stone is \( \dfrac{1936}{x} \, \text{m s}^{-2} \). The value of \( x \) ___. \( \left( \text{Take } \pi = \dfrac{22}{7} \right) \)