Room is heated by a base-board resistance heater, which is designed to heat the air in this room from 8oC to 27 oC within 20 min. Approximating the room as a thermo-insulated cuboid 15m ? 10m ? 5m and assuming the specific heats to be constant at a room temperature (300K) and pressure (100 kPa), please determine
(a). (4p) The total mass of air inside the room, in kg.
(b). (4p) The power required by the resistance heater, in kW.
Hints: It is assumed that there are no heat loss and air leakage for such a thermo-insulated room; air can be considered as an ideal gas, and the specific heat can be assumed temperature-independent (constant) for such a narrow temperature range involved; the kinetic energy and potential energy can be ignored.