Help Physics Fluids problem

1. Dec 4, 2006

RED20

Help!! Physics Fluids problem

1. The problem statement, all variables and given/known data
Water is forced out of a fire extinguisher by air pressure. How much gauge air pressure in the tank (above atmospheric) is required for the water jet to have a speed of 29.8 m/s when the water level is d=0.515 m below the nozzle?

2. Relevant equations
I tried using bernoulli's equation, p1+ 1/2*p*v1^2 + p*g*y1= p2 + 1/2*p*v2^2 + p*g*y2
I am not sure what variables I am supposed to put in where, as the diagram i am given in the question is that of a tank with a water pipe in the middle of it.

3. The attempt at a solution
I attempted to solve for p2, using p1 as atmospheric pressure, density as the density of water, v1 as 29.8m/s^2, height as 0.515. The rest of the terms on the second half of the equation I thought would cancel because the height would be 0 and I thought the starting velocity is 0. I ended up getting -4.49 x 10^5 Pa...which isn't right...please help!

2. Dec 5, 2006

OlderDan

The height of the water in the jet is below the nozzle. I think you want to either make y1 negative, or make it zero and use the .515m for y2.