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!

Fluid Hydrostatics

  1. May 31, 2015 #1
    1. The problem statement, all variables and given/known data
    Attached below

    2. Relevant equations


    3. The attempt at a solution
    My first confusion is with the pressure measuring device, i just converted the units into Pa by dividing by 1.02x10-5 such that:
    Pressure at the top of the tank = (0.07/1.02e-5) - (9800*0.3) = 3922.75Pa
    So on the cone the average pressure is (3922.75 + 0.05*9800) = 4412.75Pa
    The surface on which this force acts is the top part of the cone, where r = h*tan(30) , r = 0.0577, which means the surface is 0.031m^2
    The force acts Vertically and horizontally but the horizontal components cancel each other out (right?) So the vertical force is:
    4412.75*0.031*cos(60) = 68.4N, which isn't the correct result.

    This is the same method i was using to solve problems related to tilted rectangular plates, however now it is a conical surface should i be solving it differently ?

    Any help would be much appreciated, thank you!
     

    Attached Files:

  2. jcsd
  3. May 31, 2015 #2
    Well i think i solved it, but i don't know why the first method didn't work!

    I just considered the equilibrium of the fluid element surrounding the cone and bounded by the cylinder of radius r=0.0577.
    The volume of this fluid element is
    Vcyl - Vcone = 1.05e-3 - 3.49e-4 = 7e-4 m^3
    Weight of fluid element = 7e-4 * 9800 = 6.83N
    The upward force on this fluid element due to pressure is:
    (pi*0.0577^2*(3922.75+0.1*9800) = 51.28N
    The two horizontal forces cancel each other out thus the vertical force is 51.28 - 6.83N = 44.45N = S
    Its the right answer but maybe its just all one big coincidence!
    Could anyone confirm if this is correct, and also explain what is wrong with the first method.
    Thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Fluid Hydrostatics
  1. Hydrostatics Problem (Replies: 1)

  2. Hydrostatic force (Replies: 6)

Loading...