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!

Pressure in a Lake

  1. Oct 27, 2009 #1
    1. The problem statement, all variables and given/known data
    At the surface of a freshwater lake the air pressure is 1 atm. At what depth under water in the lake is the water pressure 4.5 atm?


    2. Relevant equations
    P=a+hgp
    h=(P-a)/(g*p)


    3. The attempt at a solution
    h=(4.5x105 - 1x105)/(9.8*1000)=35.71
    I also did the equation with 9,000 Pa converted to atm, which I think it what I'm supposed to do but I still get the incorrect answer.
     
  2. jcsd
  3. Oct 27, 2009 #2
    Convert everything to pascals before using the equations. Also, be sure that the density you have for freshwater is in kg/m3. I'm not seeing anything wrong in your method, so I'm assuming the problem is in the units.
     
  4. Oct 27, 2009 #3
    "h=(4.5x105 - 1x105)/(9.8*1000)=35.71" Appears to be correct. If I am not mistaken, 10 m of water is roughly = to 1 atm. But, I am not 100% sure off the top of my head. If that's the case, it would make sense that 35 m of water would be about 3.5 atm plus the 1 atm from the atmosphere = 4.5 atm.

    If you know, what is the answer supposed to be?
     
  5. Oct 27, 2009 #4
    Thanks, I just needed to convert the top to pascals, I thought I only had to do it to the bottom.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Pressure in a Lake
Loading...