A water heater of power $2000 \mathrm{W}$ is used to heat water. The specific heat capacity of water is $4200 \mathrm{J} {\mathrm{kg}}^{-1} {\mathrm{K}}^{-1}$. The efficiency of heater is $70\%$. Time required to heat $2 \mathrm{kg}$ of water from $10°\mathrm{C}$ to $60°\mathrm{C}$ is _____ $\mathrm{s}$.

(Assume that the specific heat capacity of water remains constant over the temperature range of the water).