A wind turbine is rotating at 22 rpm in steady state at a wind speed of 13 m/s, and producing 1.5 MW of power. The inertia of the mechanism is 3.4 x 10^6 kg-m^2. Suddenly there is a short-circuit on the electric grid, and the electrical output goes to zero for 2 seconds. Calculate the increase in speed in rpm during this interval. Assume that the shaft-torque remains constant and all other efficiencies to be 100% for the purpose of this calculation.