A classroom which normally contains 26 people is to be air- conditioned. A person in the classroom typically dissipates heat at a rate of 360 kJ/h. The room is lit with 15 light bulbs which each consume 40 W. A 200 W fan also operates in the room near a door to a computer closet. This fan pulls warm air into the classroom under the door at a rate of 200 kg/h. The room gains 10 kJ in energy (enthalpy) for each kg of warm air which enters. The air comes under the door at 10 m/s and leaves the room with negligible velocity through a large vent 3 m above the floor. Otherwise the room is well sealed. Finally, the room gains 5,000 kJ/h by heat transfer through the walls and windows. Determine the air-conditioner capacity, in kW, that is needed to keep the room at a steady temperature. Are any terms of the energy balance negligible?