Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Pressure (Net Force)

  1. Aug 2, 2008 #1
    Water stands at depth 'd' behind a dam of width 'w'.

    i.
    Find an expression for the net force of the water on the dam.

    ii.
    Evaluate the net force on a 100m high dam with a 60m water depth.

    Attempt
    For the first part:

    p=F/A
    A=wd
    pwd=F

    Then integrate from 0 to d which gives .5pw(d^2).
    Does this even look remotely correct, i have a feeling there should be a g somewhere in there?

    As for the 2nd part I'm stumped, how do I find the p term from that information.

    Any help as always is greatly appreciated :)
     
  2. jcsd
  3. Aug 2, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    How does pressure in a liquid depend upon depth?
     
  4. Aug 2, 2008 #3
    Weight of the water above it?
     
  5. Aug 2, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Give a precise formula for pressure as a function of distance below the surface. (Look it up!)
     
  6. Aug 2, 2008 #5
    P = Po + pdg

    p = density

    But how do i relate that to what I'm doing >.<
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook