1. Consider an electrical circuit with the transfer function below: G(s) = 10 s + 1 Obtain the steady-state output of the closed loop unity-feedback system when it is subjected to each of the following inputs: a) r(t) = sin(t + 30) b) r(t) = 2 cos (2t − 45) c) r(t) = sin(t + 30) − 2 cos (2t − 45) , (Hint: you can use superposition)

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.