What Gauge Pressure is Needed for a Water Jet to Reach 29.8 m/s?

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To determine the gauge air pressure needed for a water jet to reach a speed of 29.8 m/s from a fire extinguisher, Bernoulli's equation is applied. The problem involves calculating the pressure difference using the water's height of 0.515 m below the nozzle and the velocity of the water. An initial attempt to solve for pressure resulted in an incorrect value of -4.49 x 10^5 Pa, indicating a misunderstanding of the variables. The discussion suggests reconsidering the height values in the equation, particularly whether to treat y1 as negative or adjust y2 accordingly. Clarifying these variables is crucial for arriving at the correct gauge pressure.
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Help! Physics Fluids problem

Homework Statement


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?


Homework 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.


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!
 
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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.
 
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