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Homework Help: Miniature sub pressure physics

  1. Jul 1, 2007 #1
    1. The problem statement, all variables and given/known data
    A miniature sub is lowered to a depth of 8.5 m in sea water of density 1.03 grams/cc. The interior of the research craft is maintained at 1.0 atm. Find the net force that must be withstood by a 1.5 m diameter hatch which leads to the inside.

    2. Relevant equations

    Pressure = density * gravity * height
    Pressure = P (atmospheric) + density * gravity * height
    Mass = density * area* height

    3. The attempt at a solution

    Pressure = 101300 + 1030 kg/m^3 (9.81m/s^2) * 8.5m
    Once I found the pressure, I multipied it by the area (pi r^2)
    The answer I got was wrong and I'm wondering what I did wrong. Please help.
  2. jcsd
  3. Jul 1, 2007 #2
    You must consider the pressure on BOTH sides of the hatch.
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