$I_1 = 0.5 \text{ kg. } m^2, I_2 = 0.25 \text{ kg. } m^2, q = 6 \times 10^4 \frac{N.m}{rad}$ \newline $T_1 = 500 + 320 \cos 200t$. Find for the shown system: \newline a) The natural frequency \newline b) The steady state response \newline c) The total torque versus time