Write the torque equations of the gear-train system shown in Fig. 2P-14. The moments of inertia of gears are lumped as J₁, J2, and J3. Tm(t) is the applied torque; N₁, N2, N3, and N4 are the number of gear teeth. Assume rigid shafts. a. Assume that J₁, J2, and J3 are negligible. Write the torque equations of the system. Find the total inertia the motor sees. b. Repeat part (a) with the moments of inertia J₁, J2, and J3.