) A city holding tank for water sits 20 m above the city. If a house was on fire 15 m away from the base of the holding tank, and the tank was originally filled to a depth of 15 m, to what depth would firefighters have to drain the tank so water, sprayed from the bottom of the tank, hits the bottom of the house?
II) This tank is sealed air-tight with an air gap between the water’s surface and the top of the tank. The air pressure in the air gap is 30.4 kPa, while atmospheric pressure outside the tank is 101.4 kPa. Assuming the water level in the tank does not change when the water is released from its valve, to what depth will firefighters now need to drain the tank so water hits the burning house?