[wynn]

For the following question, the solution manual sets du/dt (change of internal energy) = 0.  Moreover, it also set the change of total entropy to zero. Why is that?
 
An electric motor under steady load draws 9.7 amperes at 110 volts; it delivers 0.93 kW of mechanical energy. The temperature of the surroundings is 300 K. What is the total rate of entropy generation Sg ? What is its origin ?