1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Help Physics Fluids problem

  1. Dec 4, 2006 #1
    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. jcsd
  3. Dec 5, 2006 #2

    OlderDan

    User Avatar
    Science Advisor
    Homework Helper

    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Help Physics Fluids problem
  1. Fluid physics help (Replies: 1)

Loading...