A coil of self-inductance 40 mH and internal resistance $9\Omega$ is used as a heater. It is connected to a source of alternating voltage of amplitude 300 V and angular frequency 300 rad/s and used to heat 2 kg of water placed in a vessel of heat capacity 3000 ${\text{J/}}^{\text{0}}\text{C.}$ The heat capacity of the coil is1200 ${\text{J/}}^{\text{0}}\text{C}$ Initially, the coil, the water and the vessel, all are at temperature ${\text{20}}^{\text{0}}\text{C.}$ Assuming that no heat is lost to the surroundings, and that the coil, the water and the vessel always remain at the same temperature, the time (in seconds) after which the temperature of the water has risen to ${\text{60}}^{\text{0}}\text{C}$ is ____________.(Specific heat of water ${\text{=4200\hspace{0.17em}J/kg}}^{\text{0}}\text{C)}$