A fire hose of radius 0.0300m is connected to the pump outlet on the fire truck. At the other end of the hose, water emerges through a hose nozzle of radius 0.0200 m with the average speed of 4.00m/a when the nozzle is 15m above the fire truck. At what average speed does water enter the hose? for what outlet gauge pressure is the fire truck pump set?