Solve the below problem:
Q: What diameter must a 21.0-m-long air duct have if the ventilation and heating system is to replenish the air in a room 9.0 m X 12.0m X 4.0m every 10min? Assume the pump can exert a gauge pressure of 0.71 X 10-3 atm? You should solve the problem step by step.