An aerator for a fish tank consists of a tube with internal diameter 0.2 mm connected to an air pump. The open end of the tube is at a depth of 25 cm below the water surface. Calculate the pressure (in excess of atmospheric pressure) that must be provided by the pump, if a bubble just forms at the open end of the tube. [You can assume that the surface tension of water is y = 0.072 Nm¯¹ and that its density is 1000 kg m¯³.]

An aerator for a fish tank consists of a tube with internal diameter 0.2 mm connected to an air pump. The open end of the tube is at a depth of 25 cm below the water surface. Calculate the pressure (in excess of atmospheric pressure) that must be provided by the pump, if a bubble just forms at the open end of the tube. [You can assume that the surface tension of water is y = 0.072 Nm¯¹ and that its density is 1000 kg m¯³.]