Water is supplied to a process at a rate of 5m3/min. It is supplied from a tank that is located on the roof of the plant. The water level in the tank is held constant at 20m above ground level. The water flows to an underground tank open to the atmosphere. The fill pipe of this tank is located at the top of the tank which is 3m below ground level. Ignoring pipe friction, what should be the inside diameter of the pipe