8. When the frequency on the grid changes the initial response comes from the rotating energy stored in all rotors on the grid. The rotational energy for a spinning body is Ekin w Jmech 2 (1) where J is the moment of inertia in kgm, and wmech is the mechanical angular speed. Assume a 58 MW machine with 12 pole pairs has a moment of inertia of 590'000 kgm. If the electrical frequency drops with a value of 0.05 Hz in 4 seconds calculate the power the change in frequency adds to the grid during the 4 seconds if we assume that the turbine power is constant, and that the frequency falls linearly.