A permanent magnet dc motor is to be started from rest. This motor is driving a load of inertia JL= 0.042 kg-m2, and a load torque of TL= 2 Nm. The motor current must not exceed 15A. First, find the expression of voltage va as functions of time which must be applied to bring this motor to a steady state speed of 300 rad/s as quickly as possible . Then, at time t= 1.2 seconds, what is the voltage va in Volts?