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!

Absolute pressure. depth

  1. May 4, 2005 #1
    At what depth beneath the surface of a lake is the absolute pressure 6 times the atmospheric pressure of 1.01 x 105 Pa that acts on the lake's surface?

    pressure = density * g * h

    I thought to multiply 6 * 1.10 X 10^5 pa. Then divide that answer by 1000 kg/m3 (density of water, right?) * 9.8 m/s/s.

    This was marked wrong my webassign.
    Can someone help me figure out what I did wrongly?

    Thank you.
     
  2. jcsd
  3. May 5, 2005 #2

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You were almost right, but you calculated the depth at which the change in pressure was six times the surface pressure. This makes the total pressure at that depth slightly more than six times the surface value.

    [tex]h\ =\ depth[/tex]

    [tex]P-P_s=\Delta P=\rho gh[/tex]

    [tex]\frac{P+\Delta P}{P}=6=1+\frac{\rho gh}{P}[/tex]

    [tex]h=\frac{5P}{\rho g}[/tex]

    Just a little smaller than your value. :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Absolute pressure. depth
  1. Absolute pressure (Replies: 4)

Loading...