A dc motor is to be started from rest. Jm = 0.02 kg•m2, Ra = 0.35 Ω, and La ≈ 0, Kb = 0.5 N·m/A, and no rotational loss. The motor is driving a load with Jm = 0.04 kg•m2 , and a load torque of 2 N·m. The motor current must not exceed 15 A. Calculate and plot the voltage, Vt, which must be applied to bring this motor to a steady-state speed of 300 rad/sec as quickly as possible, and speed, as functions of time.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.